🍏Physics Paper 2 Flashcards
1
Q
Phys: what are the 3 ways of accelerating
A
- Speeding up
- Slowing down
- Changing direction (because velocity is a vector quantity)
2
Q
Phys: what is the equation for acceleration
A
a = F/m
3
Q
Phys: how do you find distance on a velocity time graph
A
Area under the line
4
Q
Phys: what is a longitudinal wave
A
It is a wave where vibrations of the particles is parallel to the direction of the wave
5
Q
Phys: what is a transverse wave
A
Vibrations are perpendicular to the direction of energy transfer
6
Q
Phys: how do you calculate wave period
A
Wave period = 1/ frequency
7
Q
Phys: how do you calculate frequency
A
Frequency=number of oscillations/time
8
Q
Phys: how do you calculate wavespeed
A
Wavespeed = frequency x wavelength
9
Q
Phys: what is a rarefraction
A
This is a reduction in density
10
Q
Phys: what are p-waves
A
They are longitudinal pressure waves
11
Q
Phys: what happens to the particles after a longditudional wave passes through them
A
They stay in the same position as before the wave came
12
Q
Phys: what is wave period
A
It is the time for one wave to pass
13
Q
Phys: what are electromagnetic waves
A
They are transverse waves that travel at the same speed in the same medium, roughly 300,000,000 m/s in vaccum
14
Q
Phys: what are the 7 main types of electromagnetic wave is order of frequency from high to low
A
Gamma, x-ray, ultraviolet, visible, infrared, microwave, radiowave
15
Q
Phys: what are the uses of gamma waves
A
Medical therapy, astronomy, steralisation
16
Q
Phys: what are the uses of x-rays
A
To treat cancer and to diagnose injury
17
Q
Phys: what are the uses of ultraviolet rays
A
Sun tanning, disinfecting, photography for medicine and forensics
18
Q
Phys: what are the uses of visible light rays
A
Screens, vision
19
Q
Phys: what are the uses of infrared rays
A
Tv remotes, security
20
Q
Phys: what are the uses of microwaves
A
Signal transmission
Heating up food 🥐🥐🥐
21
Q
Phys: what are the uses of radiowaves
A
Radio and communication
22
Q
Phys: what is the range of human hearing
A
20-20000Hz
23
Q
Phys: what is infrasound
A
Sound below 20Hz
24
Q
Phys: what is ultrasound
A
Sound above 20000Hz
25
Phys: what is a photon and how fast do they move
They are packets of energy and travel at 300,000,000 m/s in a vacuum
26
Phys: what is a wave
They vibrate and oscilate and transfer energy without transferring mass
27
Phys: what is the rest position for a wave also known as
Equilibrium
28
Phys: what is the speed of sound in air and **what** affects this speed
330 m/s, the warmer the air the sound travels faster.
29
Phys: what happens to the speed of sound when the medium gets more rigid
The speed gets faster
30
Phys: how does adding particles to a gas container increase the pressure
Increased frequency of collisions between **particles** and **walls** so greater force per unit area
31
Phys: why does a container of gas get warmer when you condense it quickly
Because you do work on the gas increasing the ke and so heat
32
phys: what is the equation for force with acceleration
F = MA
33
phys: what is the equation for frequency
Frequency = number of oscillations / time
34
phys: what is the equation for wave period
1 / frequency
35
phys: what is the equation for wave speed
36
phys: what is the rest point of a wave called
equilibrium
37
phys: describe the magnetic field around a flowing charge
It forms a magnetic field in concentric circles around the charge
38
phys: what happens to the magnetic field if you increase current
It increases
39
phys: what is a solenoid
It is a coil of wire
40
phys: describe the magnetic field of a solenoid with flowing charge
41
phys: what is the equation for pressure
Pressure = force / area
42
Phys: what is the: crest, trough, equilibrium/rest position, amplitude and wavelength of a wave
43
Phys: is momentum vector or scalar
Vector
44
Phys: what is the equation for momentum with mass
45
Phys: how do you find distance traveled on a velocity time graph
Find the area under the line
46
Phys: what is happening at each point on the velocity time graph
- A - accelerating
- B- constant velocity
- C - accelerating
- D - constant velocity
- E - decelerating
47
Phys: what is an elastic object
It is an object that returns to its original shape and size when a compression/tension force is released. This is called elastic deformation.
48
Phys: what is a plastic object
It is an object that will not return to its original size and shape when a compression/tension force is released. This is called plastic deformation.
49
Phys: what is a tension force
A force that pulls apart
50
Phys: what are the 8 types of contact force
- friction
- drag
- air resistance
- water resistance
- tension/elastic
- normal contact
- thrust
- lift
51
Phys: what are the 3 non-contact forces
- gravitational
- magnetic
- electrostatic
52
Phys: what is an interaction pair of forces
It is a pair of forces that are equal and opposite
53
Phys: what is the centre of mass of an object
It is the place in an object where the weight appears to act from
54
Phys: what is the law of conservation of momentum
Momentum before and event = momentum after an event
55
Phys: what is inertia
The tendency to continue doing what your already doing
56
Phys: what are the properties of permanent magentisim
- they are always magnetic
- their magnetic field has a norths nod a South Pole
- when they are near a magnetic material they cause it to become a magnet
57
Phys: what are the 3 magnetic elements (+plus the other material you must know)
Nickel, iron, cobalt and you must know steel for the exams
58
Phys: what causes Magnetisim
a uniform direction of Electron spins
59
Phys what does the electron spin look like in magnetic materials vs non magnetic ones
In magnetic materials the electron spins are in the same orientation, they are not in non magnetic materials
60
Phys: what is a magnetic domain
It is a region in a magnetic field where the magnetic fields are in a uniform direction
61
Phys: what are the properties of induced magnets
- they have a north and South Pole (temporarily) and a magnetic field
- they can **only** be attracted by magnets and not repeled
- they are only magnets in another magnetic field
62
Phys: describe the magnetic field inside a solenoid with flowing charge
It is strong and uniform
63
Phys: what is an inelastic collision
A collision where the objects have no elasticity and so collide and stay together
64
Phys: What is the equation for change in momentum
65
Phys: Why does a crash mat work to slow soften an impact
• Increasing time taken to stop, decreases the rate of change of momentum
• This reduced the force one the person
• Leading to less damage
66
Phys: what is the electromagnetic spectrum
- it is a collection of waves each of which exists over a variety of wavelengths
67
Phys: what do waves transfer
Energy and information
68
Phys: what is it called when a wave passes through a clear surface
It is **transmitted** through the surface
69
Phys: what type of wave has the longest wavelength
Radiowaves
70
Phys: what are the properties of waves with short wavelengths
- shorter distance
- more information
- less spreading out
71
Phys: how do antennae work
When an electromagnetic wave hits an ariel it induces an alternating current in the antennae with the same frequency as the wave, this allows for information to be transferred.
72
Phys: why are microwaves and not Radiowaves used for satellite communication
Because Radiowaves cannot penetrate the atmosphere and so microwaves have to be used.
73
Phys: how do microwaves heat food
They vibrate the water molecules in the food and so cause it to heat
74
Phys: why do microwaves not affect you
Because of the mesh that has a smaller diameter than the amplitude of the wave
75
Phys: what are the risks of uv radiation
Skin cancer and eyedamage(sunglasses)
76
Phys: what part of the human body can be ionised
the atoms in the cells
77
Phys: how are atoms ionised
- electron hit by ionising radiation
- gains enough energy to escape the atom
- this creates an ion
78
Phys: what does the plum pudding model of the atom look like
79
Phys: what does the nuclear model of the atom look like
80
Phys: what does the Bohr model of the atom look like
Energy levels
81
Phys: what does the model of the atom that Chadwick developed look like
82
Phys: how are radio-waves produced
Radiowaves are produced by oscillating current in an arial or circuit with the same freq as the current
83
Phys: if light enters a denser or less dense medium and it doesn’t refract what angle has it entered or exited the medium
It has entered or exited at the same angle as the normal
84
Phys: toward what does light bend when it enters a denser medium
Toward the normal
85
Phys: toward what does light bend when it enters a less denser medium
Away from the normal
86
Phys: what is the incident ray
The incoming ray
87
Phys: what is the ray after the incident ray that in inside the new medium
Refracted ray
88
Phys: what is the ray exiting the material
Emergent/transmitted ray
89
Phys: How do you calculate change in momentum
Change in momentum = mass x change in velocity
90
Phys: how do you calculate force with momentum
Force = (change in momentum)/time
91
Phys: what happens to all emitted waves when temperature is increased
The greater the intensity of all emitted waves and the peak emitted wavelength us shorter
92
Phys: what happens to all emitted waves when temperature is decreased
The weaker the intensity of all emitted waves and the peak emitted wavelength is longer
93
Phys: why is the moon classed as a satellite
Because it orbits a planet
94
Phys: what magnetic field lines are closer together what is it called
Denser lines of flux
95
Phys: how does gravity affect the motion of a satellite
- creates a resultant force that causes **acceleration**
- it changes direction of resultant force which accelerates the satellite, which changes velocity as it is a vector
- change in velocity is acceleration
96
Phys: what is a moment
It is the turning effect of a force
97
Phys what is the equation for a moment
Moment = force x distance (from pivot)
98
Phys: what do compression and tension forces do
They stretch or compress and **do work**
99
Phys: what is doing work
Transferring energy
100
Phys: what does a tension force do
It stretches an object
101
Phys: what does a compression force do
It compresses an object
102
Phys: When the line on this graph is not straight when it is a measure of an elastic object, what has happened
It means that the spring has reached and passed its elastic limit and causes permanent plastic deformation
103
Phys: what is hooke’s law
It is a law that states that for an elastic object force is directly proportional the extension
104
Phys: how do you find the spring constant for a spring with a force extension graph
Spring constant = 1 / gradient
105
Phys: what is a resultant moment
It is a moment when the clockwise and anticlockwise aspects are not in balance
106
Phys: what do we use leavers and gears to do
We use them to transmit the rotational effect of forces from one place to another (to make the force input less)
107
Phys: what are 2 properties of gears
- they have interlocking teeth, so that I one gear is turned then the other is also
- they transmit rotational effect, from one place to annother
108
Phys: what are different sized gears used for
They are used to change the moment of a force, if we send a force to a larger gear there will be a bigger moment
109
Phys: what is pressure measured in
Pa
110
Phys: what is the force similar to buoyancy caused by water
Upthrust
111
Phys: if an object is resting on the ground what force must counteract weight
Normal contact of ground + others such as upthrust possibly
112
Phys: in equations what unit is used for area
Meters squared
113
Phys: what unit is used for pressure
Pa convert if you have kPa
114
Phys: what height is used in the atmospheric pressure equation, pressure = h x g x dencity
The height of the column above the point messured
115
Phys: How to find the average density of a colunm of fluid with changing density
Average density = pressure difference / (height x gravity)
116
Phys: when a liquid is heated it is the atmospheric pressure that stops the liquid from boiling, why would this mean that it is harder to cook something in water at sea level as opposed to the top of Everest
A liquid boils at a temperature at which its vapour pressure is equal to the pressure of the gas above the liquid. The lower the pressure of the gas above the liquid, the lower the temperature at which the liquid will boil
117
Phys: what is Newton’s first law (law of inertia)
An object in motion will remain in motion in constant speed and direction unless acted on by an unbalanced force
118
Phys: what is Newton’s third law
Every action has an equal and opposite reaction
119
Phys what is stopping distance
Thinking distance + braking distance
120
Phys: what is the principle of moments (needed for balance)
Clockwise moment = anti-clockwise moment
121
Phys: in this equation, what is v and u
122
Phys: what is a magnetic field
It is region around a magnet where another magnet or moving charged particle will be affected
123
Phys: Left hand rule
This is it
124
Phys: What is a split ring commutator
A ring on a DC motor with 2 gaps, leading to the polarity of the current being reversed every half rotation and allowing the motor to rotate continuously
125
Phys: why does light bend like it does **in the diagram**
- slows down and bends towards the normal
- speeds up as it exits and bends away from the normal
126
Phys: what are the primary colours
- red
- green
- blue
RGB
127
Phys: what are the 3 secondary colours
- **yellow**, green and red
- **magenta**, red and blue
- **cyan**, blue and green
128
Phys: how do you make yellow with 2 primary colours
Red and green
129
Phys: how do you make magenta with 2 primary colours
Red + blue
130
Phys: how do you make cyan with 2 primary colours
Blue + green
131
Phys: when white light shines on a blue selling what light reflects
Blue light is reflected and other colours are absorbed
132
Phys: when white light is shone through a yellow filter what happens
Blue light is absorbed but not red or green as they make yellow, they are **transmitted**
133
Phys: what is it called when light goes through a filter
It is transmitted through the filter
134
Phys: why do some objects appear white
They reflect all wavelengths of light
135
Phys: is background radiation ionising
YES
136
Phys: what are 2 man made sources of radiation
- nuclear power
- medical
137
Phys: what are 2 natural sources of background radiation
- cosmic rays p
- food
- rocks
138
Phys: what conclusions can you draw
- all galaxies are moving away from the sun because they are all red shifted
- c is moving away fastest as it is the most red shifted and is the furthest away as it is the most red shifted
139
Phys: how does the Big Bang theory describe the universe as it began
It was hot and dense
140
Describe the universe before it began
Hot and dense
141
Phys: how does red shift from distant galaxies provide evidence for the beginning of the universe
142
Phys: How does redshift show the universe started in one point
Red shift shows galaxies are moving away
More distant galaxies=more redshift
There is a single point of origin
More distant galaxies move away faster
143
Phys: what is a typical walking speed
1.5 M/s
144
Phys: what is a typical running speed
3 M/s
145
Phys: what is a typical cycling speed
6 M/s
146
Phys: why is the vertical resultant force if someone standing still 0
Because they are not accelerating
147
Phys: if force stays the same and friction decreases what happens to resultant force
Resistive forces decrease so resultant force increases
148
Phys: complete the diagram, **what type of lens is it**
Convex
149
Phys: complete the diagram, **what type of lens is it**
Convex
150
Phys: complete the diagram, **what type of lens is it**
Concave
151
Phys: what type wave is a sound wave
- longditudional
- mechanical
152
Phys: what is a mechanical wave
It is a wave that needs matter to travel
153
Phys: label a sound wave
154
Phys: how are frequency and amplitude linked to the sound of a sound wave
- freq - higher freq higher pitched sound
- amplitude - higher amplitude larger volume
155
P and n on battery circuit diagram
156
phys: what is a vector quantity
it is a quantity with magnitude and **direction**
157
phys: how can a vector quantity be represented
- it can be represented by an arrow
- the length represents the magnitude of the force
- the direction represents the direction of the vector quantity
158
phys: what type of quantity is force
it is a vector quantity
159
phys: what is the equation for weight
weight = mass x gravitational field strength
160
phys: what is gravitational field strength measured in in the equation for weight
newtons per kilogram
161
phys: where does the weight of an object act from
a single point called its center of mass
162
phys: what property does the weight and mass of an object have
the weight and mass of an object are directly proportional
163
phys: how is the weight of an object measured
using a calibrated spring balance
164
phys: what happens when a force causes an object to move through a distance
work is done on the object
165
phys: what does work do to an object
it causes it to move through a disacnce
166
phys: when force causes displacement of an object what does it do the the object
work
167
phys: when is one joule of work done
when a force of one newton causes a displacement of 1 meter
168
phys: what does one joule =
1 joule = 1 newton-meter
169
phys: when an object is stretched or compressed why must more than one force act on it
because one force will cause movement, check
170
phys: what is the extension of an elastic object directly proportional to
the force applied to the object, provided the **limit of proportionality is not exceeded**
171
phys:
172
phys: when the relationship between force and extension in a spring is non-linear what has happned
the limit of proportionality has been passed and permanent plastic deformation has happened, check
173
phys: what is an example of a transverse wave that is not electromagnetic
ripples on water surface
174
phys: what can happen to waves at the boundary between 2 different materials
- the wave could be reflected
- the wave could be transmitted and if there is a change in velocity there could be a refraction
175
phys: how does the ear work
- within the ear sound waves cause the ear drum to vibrate
- these vibrations cause the sensation of sound
- the conversion of these waves to sounds only works over a limited frequency range which restrict the limits of human hearing
176
phys: in different substances what do the absorption reflection and transmition of waves depend on
the wavelength of the wave, check if more cards on this
177
phys: how can radio waves be produced
by oscillations in electrical circuits
178
phys: what 2 types of changes in atoms that can cause electromagnetic waves to be released
- a change in the nuclei of an atom
- changes of an atom
check
179
phys: what does the effect of radiation depend on
- the type of radiation
- size of the dose
180
phys: what is the size of radiation dose measured in
sieverts check
181
phys: what can UV waves cause
- skin to age prematurely
- an increased risk of skin cancer
182
phys: what can X and gamma rays cause
they are ionising radiation and so can cause mutations of genes and cancer
183
Phys: what is a black body
A perfect black body is an object that absorbs all of the radiation incident on it. It does not reflect or transmit any radiation. Since a good absorber is also a good emitter a perfect black body would be the best possible emitter
184
Phys: what do all bodies do in terms of radiation
- all bodies emit radiation
- the intensity and wavelength distribution of any emission depends on the temp of the body
185
Phys: in terms of radiation what does a body at a constant temperature do
It absorbs and emits radiation at the same rate
186
Phys: what happens to a body when it absorbs radiation at a faster rate than it emits it
The bodies temperature increases
187
Phys: what, in terms of radiation does the temperature of the earth depend on, and what else
- many factors
- the rate of absorption and emission of radiation
- the reflection of radiation into space
188
Phys: what are the poles of a magnet
They are the regions in a magnetic field where it is strongest
189
Phys: what happens when 2 magnets are brought close together
They exert a force on one another
190
Phys: what is a magnetic field
It is the region around a magnet where a force acts on another magnet or on a magnetic material
191
Phys: what is the force between a magnet and a magnetic material
It is always a force of attraction
192
Phys: what does the stregnth of a magnetic field depend on
distance from the magnet
193
Phys: where is a magnetic field strongest
It is strongest at the poles of the magnet
194
Phys: how do you find the direction of a magnetic field at any point
It is the direction of the force that would act on another north pole placed at that point, it is the line from the north pole of the magnet to the south
195
Phys: how does a compass work
- compasses contain a small bar magnet
- the earth has a magnetic field
- the compass needle points in the direction of the earth's magnetic field
196
Phys: (magnetism) what happens when current flows though a conducting wire
A magnetic field is produced, its strength depends on the current through the wire and the distance from the wire
197
Phys: by changing the shape of a straight wire how can you increase the magnetic field
Shaping it to form a solenoid
198
Phys: how can you increase the strength of the magnetic field of a solenoid
You can add an iron core
199
Phys: what is an electromagent
It is a solenoid with an iron core
200
Phys: for a conductor at r**right angles to a magnetic field carrying a current** what is the equation for the force
Force = flux density X current x length
201
Phys: what must you know that is in our solar system
- one star (the sun)
- 8 planets orbiting the sun
- dwarf planets
- natural satellites (moons)
202
Phys: what is our solar system a small part of
The milky way (our galaxy)
203
Phys: how was the sun formed
It was formed from a cloud of dust and gas pulled together by gravity
204
Phys: how are stars formed in nebulae
At the beginning of the stars lifecycle dust and gas from a nebula is pulled together until the conditions are met for fusion to occur, the pressure from the fusion reactions and the gravitational collapse of the star reach equilibrium
205
Phys: what is the life cycle for a star of a similar size of the sun
- protostar
- main sequence
- red giant
- white dwarf
- black dwarf
206
Phys: what is the life cycle for a star much larger than the size of the sun
- protostar
- main sequence
- red **super giant**
- supernova
- either a neutron star or a black hole
207
Phys: what factor determines the life cycle of a star
The size of the star
208
Phys: what produces all of the naturally occurring elements
Fusion processes
209
Phys: what distributes elements around the universe
The explosions of massive stars (supernova)
210
Phys: how do fusion processes lead to the formation of new elements
211
Phys: in a stable orbit, if the speed changes what must happen
The radius of the orbit must change, check
212
Phys: there are still many things that we do not know about the universe, what is ane example
- dark mass
- dark energy
213
Phys: what is red shift in relation to the big bang
There is an observed increase into the wavelength of light from the most distant galaxies (red shift), the further away they are the faster they are moving and the bigger the observed red shift, this is evidence for the big bang as it shows the universe is expanding
Check and possible question change
214
Phys: what does the big bang theory suggest about the origins of the universe
That it began from a very small region that was extremely hot and dense
215
Phys: what do observation of distant supernovae suggest, since when
Since 1998 onwards observation of supernovae suggest that distance galaxies are reseding even faster
216
Create flashcard on this
217
Phys: what 2 things can be used to transmit rotational effect
- gears
- levers
218
Phys: how does pressure in fluids cause a pressure at the normal
219
How do gears and levers transmit rotational effect
220
Phys: what is area measured in
Meters squared
221
Phys: what can extension be in the equation force = spring constant x extension
- compression
- extension
222
Phys: what does a force that stretches (or compressed) do
- it does work
- stores elastic potential energy in a spring
223
Phys: if a spring is compressed or extended, and the elastic limit has not been surpassed, what is the relationship between work done and EPE stroed
They are equal
224
Phys: what is height normally measured in in most equations
meters
225
Phys: how does buoyancy work
- a partially (or totally) submerged object experiences a greater pressure on the bottom surface than the top
- this created a resultant force upwards
- this is called upthrust
226
Phys: what factors affect floating and skinking
- volume and shape
- density (greater density than the liquid and it will sink and less and it will float)
227
Phys: if an object has a greater density that a liquid that it is placed on the top of, what will happen?
It will sink
228
Phys: what is the atmosphere
It is a thin layer (relative to the size of the earth) of air around the earth.
229
Phys: what happens to the atmosphere when altitude increases
The density of the atmosphere gets less
230
Phys: what creates atmospheric pressure
Air molecules colliding with a surface
231
Phys: what happens to the atmospheric pressure with increasing height
- the number of air molecules (and so the weight of air) above a surface decreases as the height of the surface above the ground increases
- so as height increases there is always less air above a surface than there is at a lower height
- so atmospheric pressure decreases with increasing height
232
Phys: what is distance
It is how far an object moves (without direction), so is scalar
233
Phys: what is displacement
It includes distance moved, measured in a straight line from start point to finish, and the direction of that straight line, so is vector
234
Phys: what is the gradient of an objects distance time graph
Its speed
235
Phys: how can you measure the speed of an accelerating object from a distance time graph
Draw a tangent, measure the gradient
236
Phys: how can the acceleration of an object be calculated from its velocity time graph
Calculating the gradient
237
Phys: what does this equation apply to
**uniform acceleration**
238
Phys: what can breaking distance be affected by
Adverse road and weather conditions and poor condition of the vehicle
239
Phys: what do adverse road conditions include
Wet or icy conditions
240
Phys: what are poor vehicle conditions limited to
The vehicles breaks or tires
241
Phys: what must the transfers be in for the law of conservation of momentum to be in place
In a closed system, check
242
Phys: force = (something of) momentum
Rate of change of momentum
243
Phys: what is the image for a ray diagram for a convex lens
244
Phys: what is the image for a ray diagram for a concave lens
245
Phys: why does magnification not have a unit
Because it is a ratio
246
Phys: should image and actual height both be measured with the same measurment
Yes both in mm or cm
247
Phys: what is the motor effect
When a conductor carrying a current is placed in a magnetic field, the magnet producing the field and the conductor exert an force on each other. This is called the motor effect
248
Phys: what is Fleming's left hand rule
249
Phys: what factors affect the size of the force exerted on the conductor in the motor effect
- strength of the magnetic field
- length of the conductor in the field
- the current flowing through the wire
250
Phys: what does the strength of a magnetic field around a wire with a flowing charge depend on
- the current
- the distance through the wire
251
Phys: what is a way, by changing the shape of a wire, that its magnetic field can be increased (with a flowing charge
Shaping it to form a solenoid
252
Phys: what is the magnetic field around a solenoid resembalent to
That of a bar magnet
253
Phys: how can you increase the effect of a solenoid
By putting a bar magnet inside of it
254
Phys: what is an electromagent
It is a solenoid with an iron core
255
Phys: what force allows planets and satellites to maintain circular orbits
grvaity
256
Phys: what are transformers made of
- a primary and secondary coil
- an iron core
257
Phys: why is iron used in transformers
Because it is easily magnetised
258
Phys: what is the equation for transformers
259
Phys: what does the ratio of p.d across primary and secondary coils depend on
The ratio of the number of turns on each coil
260
Phys: what would be true if transformers were 100% efficient
The electrical power output would equal the electrical power input
261
Phys: what is the equation for power in transformers
262
Phys: What effect do microphones use
Generator effect
263
Phys: what do microphones use the generator effect to do
They used the generator effect to convert the pressure variations in sound waves into variations in current in electrical circuits
264
Phys: how does the moving coil microphone work
265
Phys: what is the generator effect used for
- it is used in an alternator to generate AC
- it is used in a dynamo to generate dc
266
Phys: what are the graphs of p.d generated against time for a dynamo and for a altenator
267
Phys: how is the generator effect used in an alternator to generate ac
268
Phys: how is the dynamo effect used in an alternator to generate dc
269
Phys: what does a current carrying wire in a magnetic field tend to do
They tend to rotate, this is the basis of an electric motor
270
Phys: what effects do loudspeakers and headphones use to opperate
The motor effect
271
Phys: how is the motor effect used in loudspeakers and headphones
They convert variations in current in electrical circuits to the pressure variations in sound waves
272
Phys: how does a moving cold loudspeaker and headphones work
273
Phys: what is specular reflection
It is a smooth surface in a single direction
274
Phys: what is diffuse reflection
It is reflection from a rough surface causing scattering
275
Phys: how do colour filters work
They absorb certain wavelengths (and colour) and transmit other wavelengths (and colour)
276
Phys: what is the colour of an opaque object determined by
It is determined by which wavelengths of light are more strongly reflected, wavelengths that are not reflected are absorbed. If all of the wavelengths are reflected equally the object appears white. If all wavelengths are absorbed the object appears black
277
Phys: what are objects that transmit light
They are:
- transparent
- translucent
278
Phys: how does a lens form an image
By refracting light
279
Phys: what happens when a convex lens affects light
In a convex lens parallel rays of light are brought to a focus at the principle focus.
280
Phys: what is the focal length
It is the distance from the lens to the principle focus
281
Phys: what are ray diagrams used for
The are used to show the formation of images by convex and concave lenses
282
Phys: what type of image can be produced by a convex lens
- real image
- virtual image
283
Phys: what can the image produced by a concave lens be
Only virtual
284
Phys: what equation can be used to find the magnification produced by a lens
285
Phys: near the earths surface what is its acceleration
9.8 m/s2
286
Phys: in the equation below what is s
It is distance
287
Phys: what happens when an object falls through a fluid
It initially accelerates due to the force of gravity, eventually the resultant for will be 0 and the object will move at its terminal velocity
288
Phys: what is the velocity time graph for an object that reaches terminal velocity
289
Phys: what is the acceleration of an object directly proportional to
The resultant force (f = ma)
290
Phys: what is the acceleration of an object inversely proportional to
The mass of the object (f = ma)
291
Phys: what is the inertial mass of an object a measure of
How difficult it is to change the velocity of an object
292
Phys: what is inertial mass determined as
It is the ratio of force over acceleration
293
Phys: what symbol is for approximate values
~
294
Phys: what happens to stopping distance, for a given breaking distance, if there is a greater speed
There is a greater stopping distance
295
phys: how do brakes work
When a force is applied to the brakes of a vehicle, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases
296
Phys: in relation to brakes what are the dangers of larger decelerations
- they may lead to breaks overheating
- they could lead to a loss of control
297
Phys: the greater the speed of the vehicle what happens to braking force
The greater the speed, the greater the braking force needed to stop the vehicle **in a certain distance**
298
Phys: what happens to ultrasound waves when they meet the boundary between 2 different media
They are partially reflected when they meet the boundary between 2 media
299
Phys: how can ultrasound waves be used to to measure the distance to the boundary of 2 media
The time taken for the reflections created when the waves created at the boundary can be measured by a detector and then can be used to determine how far away the boundary is
300
Phys: what 2 things can ultrasound waves be used for
- medical imaging
- industrial imaging
301
Phys: what produces siesmic waves
They are produced by earthquakes
302
Phys: what are p-waves
They are **longitudinal** seismic waves
303
Phys: what materials do p-waves travel at different speeds through
- solids
- liquids
304
Phys: what are s-waves
They are transverse seismic waves
305
Phys: what materials can s-waves travel through
They **cannot** travel through liquid
306
Phys: what do we use to provide evidence for the structure and size of the earths core
- s-waves
- p-waves
307
Phys: wat is echo sounding
It is using high frequency sound waves to detect objects in deep water and measure water depth
308
Phys: what did the study of seismic waves provide new evidence for
It led to evidence that led to discoveries about parts of the earth which are not directly observable
309
Phys: what is the generator effect
- if an electrical conductor moves relative to a magnetic field, or if there is a change in the magnetic field around a conductor, a potential difference is induced across the ends of the conductor.
- if the conductor is part of a complete circuit, a current is induced in the conductor
- this is called the generator effect
310
Phys: in the generator effect, what does the induced current do
An induced current generates a magnetic field that opposes the original change (that produced it), either the movement for the conductor or the change on the magnetic field, check
311
Phys: what do all bodies do, no matter what the temperature
They emit and absorb infrared radiation
312
Phys: the hotter the body what happens to the infrared radiation produced
The hotter the body the more infrared radiation it radiated in a given time
