Physics Flashcards
1
Q
Induction
A
Process in which an object is charged without coming in contact with it
2
Q
Polarisation
A
separation of positive charges
3
Q
pd def
A
amount of energy required to move one unit of charge from one point to another
4
Q
resistance
A
resistive force hindering the flow of electrons
5
Q
voltage in series
A
added
6
Q
voltage in parallel
A
same
7
Q
current in series
A
same
8
Q
current in parallel
A
added
9
Q
resistance in series
A
added
10
Q
resistance in parallel
A
1/R=1/R1+1/R2+1/R3
11
Q
cell voltage in series
A
added
12
Q
current
A
rate of flow of electric charge through a circut
13
Q
physics formulae for p(resistivity)
A
p=R*L/a
14
Q
p(resistivity) forula 2
A
p = R+A^2
15
Q
Ohms law
A
v
___
(r*i)
16
Q
4 triangles in physics
A
(((v))) . (((q))) . (((e/w))) . (((e/w)))
(r * I) . (I * t) . ((t * p)) . ((q *v))
17
Q
diode
A
controls direction of current
high resistance in other direction
18
Q
wires
A
brown = live
blue = neutral (0 V)
green/yellow/red = earthing
19
Q
brown wire
A
live wire
20
Q
green yellow red wire
A
earthing wire
21
Q
blue wire
A
neutral wire (0 V)
22
Q
Ferromagnet
A
metal alloy that can be magnetised
23
Q
non-magnetic metals
A
zinc copper brass tin aluminium
24
Q
Faradays law
A
induced emf is directly proportional to the rate of change in magnetic field
25
Lenz law
induced current flows in opp direction to charge produced
26
flemings right hand rule vs left hand
right hand = generator
left hand = motor
27
Non-ferrous/Non-magnetic
materials Examples
Plastic Wood Rubber
28
Ferrous/Magnetic
materials
Examples
Iron nickel cobalt
29
Avg speed formula
Total dist/time
30
Why is avg speed diff from actual speed
For them to be equal the actual speed should be constant
31
What is velocity
Includes the speed and the direction of travel
32
What quantity is velocity
| Scalar or vector
Vector quantity
33
Diff between vector and scalar quantities
Vectors have magnitude and direction, scalars only have magnitude.
34
Isotopes def
Element having same no of protons but diff no of neutrons
| They have diff masses, diff physical properties
Same chemical propertie
35
Atomic no (Z)
Proton no (no of protons)
36
Mass no (A)
Nucleon no
| No of protons + neutrons
37
a
____X
z
a = mass no
x = element symbol
z = atomic no
38
nucleur radiation def
Tiny particles and waves of energy that radiate from an unstable and disintegrating nucleus
39
Radioactive material
Material which emits nucleur radiation (tiny particles and waves of energy)
40
Radioactive decay
Disintigration of unstable nuclei
41
Eg of stable isotopes
Carbon 12 & 13
Potassium - 39
42
Eg of unstable nucleus
Carbon-14
Potassium - 40
Uranium - 234, 235 & 238
43
Ionizing effect
Nucleur radiation can remove electrons from atoms in its path. This is called the ionizing effect
44
What happens if gas is ionized
Its conducts electricity
45
What happens if living things are ionized
Cells are destroyed or damaged
46
Radiation can be dectected by
Geigher -Müller tube
47
Charges of radiation
Alpha = +2
Beta = -1
Gamma = 0
48
Speed of gamma
Speed of light
49
Speed of alpha
0.1 *speed of light
50
Speed of beta
0.9 * speed of light
51
Main source of background radiation
Radon from ground
52
Radioactive decay
A radioisotope (unstable arrangement
of neutrons and protons) is altered to make a more
stable arrangement.
53
Half-life of a radioisotope:
Half-life of a radioisotope: is the time taken for half the nuclei present in any given sample to decay
54
Activity (radioactivity) Definition
The no of disintegrations per second in a radioactive sample
55
Activity (radioactivity) SI Unit
becquerel (Bq)
56
Beta - does what
Converts neutrons to protons
57
Beta + does what
Converts protons to neutrons
58
Alpha emmision used to make what stable
Heavy isotope (proton no >83)
59
Rutherford’s Experiment
Rutherford concluded that the atom must be largely
empty space, with its positive charge and most of its
mass concentrated in a tiny nucleus.
60
Safety Precautions
with radioactive materials
* Radioactive material is stored in a lead container
* Picked up with tongs, not bare hands
* Kept away from the body and not pointed at people
* Left out of its container for as short a time as possible
61
BROWNIAN MOTION
Gas molecules move randomly. This is because of
repeated random collisions with other gas molecules,
which constantly change the direction they move in.
Small molecules move much faster and have higher
energy than larger molecules. They can effectively move
large molecules due to repeated random bombardmentthis can be seen by larger smoke particles moving.
Therefore, the random motion of particles in a
suspension is evidence for the kinetic molecular model of
matter.
62
Micrometer screw gauge measures what?
Diameter of wire or thickness of glass
63
Vernier calliper measures what?
dist between two sides of a surface
64
Density formula
Mass/volume
65
Power formula
| With pd and current
P = V * I
66
Flemings left hand rule is for
DC Motors
67
How can we figure out direction of the wire turning in Dc motors
Fleming left hand rule
68
How can we figure out direction of the wire turning in AC Genrator
Fleming right hand rule
69
Flemings right hand rule is used for
AC Genrators
70
Negative acceleration is also called
Deceleration
71
Acceleration
Change in velocity (Δv) over the change in time (Δt),
72
Acceleration formula
((Final speed + initial speed)/2)*time
73
When deceleration is caused
by air resistance
acceleration by gravity
74
Mass definition
A measure of matter in a body and the body's resistance to motion
75
Weight definition
Weight is the force of gravity on a body as a result of its mass
76
Weight formula
Mass * G (acc due to gravity)
| Acceleration due to gravity = 9.8m/s^2
77
SI unit of mass
Kilogram (kg)
78
SI unit of weight
SI unit is Newton (N)
| which is the same as kg⋅m/s2
79
Density (p) formula
Mass (m) / Volume (V)
80
What is density
The amount of matter in a fixed volume of a body
81
How to find mass of liq
To find the mass of the fluid,
weigh it in a container, pour it out, weigh the empty container, and subtract the mass of the empty container from the full container.
82
How to find volume of liq
To find the volume of the fluid, you simply measure it very carefully in a graduated cylinder.
83
Find mass of solid
Use balance to find weight
84
To find volume of irregular obj
To find out volumeof an irregular object,
put object into a measuring cylinder with water and the rise of water is the volumeof the object.
85
Lower density floats or sinks
Lower density floats
86
Force formula
Force = Mass * Acceleration
87
Newton definition
1 newton is the force required to give 1kg an acceleration of 1m/s^2
88
Friction def
Friction:
the force between two surfaces which impedes motion and results in heating
| Eg - Air resistance
89
Newtons first law
If no external force is acting on it, anobject will, if stationary, remain stationary, and if moving,keep moving at a steady speed in the same straight line.
90
Newtons second law
F = ma
91
Newtons third law
if object A exerts a force on object B,then
object B will exert an equal but opposite force on object A
92
An object at steady speed in circular orbit is always accelerating even though speed is constant. How?
as its direction is changing, but it gets nocloser to the center.
93
Centripetal force Definition
Centripetal force is the force acting towards the center of a circle.
It is a force that is needed, not caused, by circular motion.
94
Eg of centripetal force
For example, when you swing a ball on a string round in a circle, the tension of the string is the centripetal force.
95
When you swing a ball on a string round in a circle, the tension of the string is the centripetal force.
If the string is cut then how will the ball travel (related to direction) ?
If the string is cut then the ball will travel in a straight line at a tangent to the circle at the point where the string was cut.
96
Centrifugal force definition
Centrifugal force is the force acting away from the center of a
circle.
The centrifugal force is the reaction to thecentripetal force.
It has the same magnitude (amt of force) but opposite direction to centripetal force.
97
Eg of Centrifugal force
When a car in motion takes a sudden turn towards left, passengers in a car experiences an outward push to the right.
98
Centrifugal vs Centripetal force
Centripetal force is the force acting towards the centre of the circle.
Centrifugal force is the force acting away from the centre of the circle.
Centripetal force is needed for circular motion. Centrifugal force is caused by centripetal force.
Both have the same magnitude but act in opp diections.
99
A Moment definition
| (force and motion)
A moment is a measure of the turning effect on a body
100
Moment formula
| (force and motion)
Moment (Nm) = Force (N) * Perpendicular dist from centre (m)
| A moment is a measure of the turning effect on a body
101
Ways to increase moment of force
* Increase dist from centre
* Increase force
102
levers are force magnifiers as
Turning a bolt is far easier with a wrench because the perpendicular distance from pivot is massively increased, therefore so is the turning effect
103
Equilibrium
the condition of a system when neither its state of motion nor its internal energy state tends to change with time.
In equilibrium,
clockwise moment = anti clockwise moment
there is no resultant force acting on the body.
104
How can equilibrium be proven
This can be proven by hanging masses of the same weight on opposite sides of a meter rule on a pivot at equal distances from the pivot showing that the meter rule in stationary.
105
Centre of mass definition
Centre of mass: imaginary point in a body where total mass of body seems to be acting.
| Mass on all sides of the pt are equal
Eg in sphere, its at the exact ce
106
Scalar quantity
A scalar is a quantity that only has a magnitude (so it be positive) for example speed.
107
Vector quantity
A vector quantity has a direction as well as a magnitude,for example velocity, which can be negative.
108
Momentum formula
mass *velocity
| strength or force gained by motion or by a series of events
109
What is momentum
strength or force gained by motion or by a series of events
110
what is the principle of conservation of momentum
The principle of conservation of momentum states that if two objects collide, then the total momentum before and after the collision will be the same if there is no external force acting on the colliding objects.
| mA uA+mB uB = mA vA+mB vB
m=mass
u=Initial Velocity
v = final velocity
111
What is impulse
Impulse is a certain amount of force you apply for a certain amount of time to cause a change in momentum.
112
Impulse formula
| Impulse symbol = J or IMP
IMP(J) = F(force) x t(time)
or = mv − mu (change in velocity)
Amt of force applied for amt of time causing change in momentum
| Impulse
## Footnote
product of force and time for which it acts
113
Energy definition
Energy:
amount of work and its measured in Joules (J)
| An object may have energy due to its motion or itsposition
114
SI Unit of energy
Joules (J)
115
What is conservation of energy
Conservation of energy: energy cannot be created or destroyed, when work is done, energy is changed from one form to another.
116
Kinetic energy is formed due to what?
Kinetic energy is due to motion
117
Gravitational energy
The potential of an obj to fall
118
Where is chemical energy found
In chemical bonds
119
What is nucleur energy
Atoms rearranged / split
120
Internal energy is due to
the motion of molecules
121
What is electrical energy
Energy carried by electrons
122
What is light energy
Energy carried in light waves
123
Sound energy
Energy carried in sound waves
124
Kinetic energy formula
K.E. = 1/2 x M x V^2
| 0.5 x Mass x Velocity x Velocity
125
Gravitational Potential energy Formula
| G.P.E
G.P.E = mgh (mass x gravity x height)
| g = acc due to gravity
126
Efficiency definition
Efficiency: how much useful work is done with energysupplied
Due to the processes through which energy transferstake place not
being 100% effi cient, energy is lost to thesurrounding and
therefore energy gets more spread out(dissipated)
127
Eficiency formula
(Useful energy output /Energy input ) x 100
or
(Useful power output /power input ) x 100
128
Fuel Advantages and disadvantages
| burnt to make thermal energy,makes steam, turnsturbine
Advantages
Cheap, Plentiful,Low-tech
Disadvantages
Harmful wastes:(Greenhouse/pollutant gas,
Radiation)
129
Wave energy: (advantages and disadvantage )
generators driven by up and down motion of waves at sea.
+No greenhousegases produced
- Difficult to build
130
Tidal energy: (adv and disadvantages)
dambuilt where rivermeets sea, lake fi llswhen tides comesin & empties whentide goes out;water fl ow runsgenerator
+ No greenhousegases produced
- Expensive
- Can’t be built everywhere
131
Hydroelectric: (+ & -)
river& rain fill up lake behind dam, water released, turns turbine ∴ generator
+ Low impact on environment
+ Energy produced at constant rate
- Few areas of theworld suitable
132
Geothermal: (+ & - )
water pumped down to hot rocks rising as steam
+ No CO2 produced
- Deep drilling
- difficult and expensive
133
Nuclear fission: (+ & -)
uranium atoms split by shooting neutrons at them
+ Produces a lot of energy with very little resources
- Produces radioactive waste
134
Wind: (+ & -)
windmills are moved by the breeze. They generate electricity from kinetic energy.
+ No CO2/Greenhouse gasses produced
- Few areas of theworld suitable
135
Solar panels:
absorbs energy and use it to heatwater
+ No CO2 produced
- Variable amount of sunshine in some countries
136
Solar cells/photovoltaic cells: (+ & -)
made of materials that deliver electrical current when it absorbs light
* + No CO2 produced
- Variable amount of sunshine in some countries
137
When is work done
Work is done when force makes something move
138
SI UNit of work
J (Joule)
139
Work formula
Work (Nm) = Force (N) x Distance(m)
| Nm (Newton metre) is the same as J (Joule)
140
Δ means
change in something (eg ΔE means change in energy)
141
Joule def
1 joule of work = force of 1 Newton moves an object by 1meter
142
Power def
Rate of work
143
SI unit of power
Watts (W)
144
Power (w) formula
Work done (J) / Time taken (S)
145
Pressure def
Force per unit area
146
Pressure (Pa) formula
Force(N)/Area(m^2)
147
SI Unit Pressure
Pascal (Pa)
| Pa = N/m^2
148
Pressure in liquids formula
p = ρ g h ,
p is the pressure,
h is the depth of the liquid,
ρ is the density of the liquid,
g is the acceleration due to gravity.
149
What happens to pressure when depth of a fluid increases
Pressure increases
| P =p g h
150
Pressure is measured using
Manometer and Barometer
151
What does manometer measure
* Measures the pressure difference
* The height diff erence shows the excess pressure in addition to the atmospheric pressure.
| Pressure
152
What does barometer measure
* Tube with vacuum at the top and mercury filling the rest.
* Pressure of the air pushes down on reservoir, forcing mercury up the tube.
* Measure height of mercury
* ~760 mm of mercury is 1 atm.
| Measures atmospheric pressure in atm
153
1atm in mm
1atm = 760 mm
154
Evaporation
It is the escape of more energetic particles from thesurface of a
liquid
155
What happens to the the liquids temp after most of it evaporates
If more energetic particles escape, the liquid contains few high energy particles and more low energy particles so the average temperature decreases.
| So, a body in contact with an evaporating liquid will
subsequently cool.
156
Evaporation can be accelerated by:
* Increasing temperature: more particles have energy to escape
* Increasing surface area: more molecules are close to the surface
* Reduce humidity level in air (draught): if the air is less humid, fewer particles are condensing.
| Evaporate
energetic particles (having high temp) escape
∴ temp is less
157
How is pressure related to volume in a gas
Pressure is inversely proportional to volume
If the volume increases and the temperature stays constant, the particles hit the surface less often, thus decreasing the pressure.
158
Why is pressure inversely proportional to volume of a gas
If the volume increases and the temperature stays constant, the particles hit the surface less often, thus decreasing the pressure.
P1 V1 = P2 V2
PV = constant
159
Formula for changing pressure in gas
P1 V1 = P2 V2
PV = constant
The constant is valid at a fixed mass of gas at a constant temperature.
160
How does the temp affect KE in gas
As the temperature increases of a fixed mass of gas, the pressure increases as the average kinetic energy increases…
161
What happens to solids liquids and gasses on heating
They expand as the particles get more kinetic energy and move/vibrate faster and causes them to become further apart, taking up a greater volume.
162
Expansion due to heat is the greatest in which state of matter
Gas then liquid then solid
| Due to difference in molecular structure of different states of matter
163
Frequency def:
the number of waves passing any point persecond
measured in hertz (Hz)
164
Frequency:
the number of waves passing any point persecond
measured in hertz (Hz)
165
More thermal energy is transfered if
The temp diff across opp ends of metal is increased
166
Worst conductor in states of matter
gasses then liq
167
Is water a good thermal conductor
No
168
Conduction
Conduction
is the flow of heat through matter from places of
higher temperature to places of lowertemperature without movement of the matter as a whole. When material is heated, particles move faster, push neighbouring particles and those speed up too,
This way energy is transfered
Metals are good conductors as along with this they have many electrons that are looseand free that speed up when the metal is heated. As the electrons move freely, they collide with atoms, making them vibrate faster, therefore thermal energy is transfered to all parts.
169
Conduction metals vs non-metals
In non-metals - when heat is supplied to something, its atoms vibrate faster and pass on their vibrations to theadjacent atoms.
In metals – conduction happens in the previous way andin a quicker way –electrons are free to move, they travelrandomly in the metal and collide with atoms and pass onthe vibrations Good conductors are used whenever heatis required to travel quickly through something
170
Convection def
Convection
is the flow of heat through a fluid from places of
higher temperature in places of lower temperature by movement of the fluid itself.
171
Does convection happen when water is heated at the top
When water is heated, it expands as particles move faster taking up more space making less dense
Since the water is at the top is less dense, it floats
172
Convention current
As a fl uid (liquid or gas) warms up, the particles which arewarmer
become less dense and rise.
They then cool and fall back to the heat source, creating acycle
called convection current.
As particles circulate they transfer energy to otherparticles. If a
cooling object is above a fl uid it will create aconvection current
as well.
173
Suns energy travels to us in the form of
electromagnetic waves
like infrared waves and light
| This is also called thermal energy
174
What does thermal radiation include
Mainly infrared waves but very hot objects also include light energy
175
Emitters
Objects that send out thermal radiation
176
Which colour is the best emmitter of thermal energy which and colour is the worst
Best - Black
Worst - white/silvery
| This is bc white/silver reflect mst of the thermal energy away
177
Why in hot countries houses are painted white
White reflects most of the thermal energy keeping the house cool
178
Best colour for absorbing thermal enrgy
Best - black
Worst - silver/white
179
Best and worst colour for reflecting thermal energy
Best - White/silver
Worst - black
180
How to increase sensitivity in a thermometer
To increase sensitivity:
* Thinner capillary
* Less dense liquid
* Bigger bulb
181
Ways to increase evaporation
* Increase Temp (more particles get more energy to escape)
* Increase Surface Area (more molecules collide with surface)
* Reduce humidity (reduced water vapour content increases time taken for molecules to condense back to liquid)
* Blow air across the surface (the air carries escaping water molecules away before they can return to liquid)
182
Sublimation
Change from solid to gas
| Eg - iodine crystals
183
does evaporation cool/heat
evaporation cools as water droplets/vapour takes thermal energy away
184
does evaporation cool/heat
evaporation cools as water droplets/vapour takes thermal energy away
185
How does kinetic theory explain cooling effect of evaporation
If faster (hotter) particles escape the liquid, the slower (cooler) ones are left behind so temp reduces
186
Specific heat capacity formula
Energy (J)/mass(kg)
187
Frequence formula
1/period
188
Period definition
Period:
time taken for one oscillation in seconds
189
Wavelength: definition
Wavelength:
distance between a point on one wave to thecorresponding point on the next wave in length
190
Amplitude def
Amplitude:
maximum displacement of a wave from itsundisturbed
point
191
Speed of wavelength is measured in
Speed:
how fast the wave travels measured in m/s
192
Wavefront def
Wavefront:
the peak of a transverse wave or thecompression of a
longitudinal wave
193
Transverse waves
Transverse Waves
* Travelling waves in which oscillation is perpendicularto direction of travel
* Has crests and troughs
* For example, light, water waves and vibrating string
194
Longitudinal waves
Longitudinal Waves
* Travelling waves in which oscillation is parallel to direction of travel.
* Has compressions and rarefactions
* For example, sound waves
195
In wave speed formula
Speed (sec) = frequecy(Hz) x wavelength(λ)
(v = fλ)
Dist per sec = no of oscillations per sec * dist between wavefronts
196
Wavelength symbol
λ
197
λ
Wavelength
198
Frequency unit
Hertz (Hz)
199
Why does refraction happen
When waves change medium, they slow down,
Since (v=fλ) and frequency (f) should remain constant, decrease in speed causes decrease in wavelength (waves become closer to each other)\
When they become closer to each other, direction changes
200
When do waves slow down
When they pass from a rarer to denser material
201
When wave slows down, it refracts where in relation to normal
It refracts towards normal (i>r)
202
When wave speeds up, it refracts where in relation to normal
It refracts away normal (i
203
Effect on wavelength from deep to shallow water
Deep water to shallow water:
speed decreases,
wavelength decreases,
and frequency remains constant
204
Effect on wavelength from shallow to deep water
Shallow water to deep water:
speed increases
wavelength increases,
and frequency remains constant
205
Reflection
Reflection:
* Waves bounce away from surface at same angle they strike it
* Angle of incidence = angle of refl ection
* The incident ray, normal and reflected ray all lie on the same plane.
* Speed, wavelength and frequency are unchanged by reflection
206
Properties of virtual image formed by plane mirror
* Image is the same size as the object
* Image is the same distance from the mirror as object
* A line joining corresponding points of the image and object meet the mirror at a right angle
* Image is virtual: no rays actually pass through theimage and the image cannot be formed on a screen
207
What causes sound
Vibration
208
What type of waves is sound
Transverse
209
What do sound waves need to exist
medium
210
What states of matter can sound travel through
Solid, liquid and gas
211
Which can happen to sound waves
| Refraction and reflection and diffraction
Refraction and reflection
Sound waves can also be diffracted (as we can hear someone even though we cant see them)
212
Sound waves can be seen by
Microphone and oscilloscope
(vibrations changed into electrical oscillations
produces waveform (graph))
213
Speed of Sound depends on
* Temp (more heat, more spped)
* Medium (faster in solids, then liquids slowest in gases)
Doesnt depend on pressure of air
214
Speed of sound formula
Dist travled(m)/time taken (s)
| unit = m/s
215
Which is faster speed of light or sound
Sound is slower than light
(eg - lightning and thunder (by 3 sec))
216
Sounds are louder at night as
At night the ground cools faster
Sound waves travel slower in cool temp
So waves leaving the ground tend to bend closer back to the ground due to refraction
217
Echo
Reflected sound a short time after it is produced
218
Echo formula
Speed of sound = Dist/time
=(2 x dist from wall)/echo time
219
Echo is used in
* Parking sensors (detect how far obstacle is from car)
* Echo sounder (measures depth of water under boat)
* Radar (uses microwaves instead of soundwaves) (detects position of aircraft/ship by measuring time taken of echo to reflect back to itself)
220
High pitch has what frequency
High pitch
221
Low pitch has what frequency
Low pitch
222
If pitch increases by one octave, frquency..
frequency doubles
223
Doubling the amplitude in sound waves affects energy/sound by...
Energy/sound ifs four times of what it used to be
224
Ultrasound Waves:
high frequency sound waves,
medically used to look at structures and organs inside thehuman body, i.e. to form an
image of a fetus in a pregnancy
225
What happens to light when it hits a black surface
It is absorbed
226
Properties of light
* Form of radiation
* travels in straight lines
* transfers energy
* travels as waves
* can travel trough empty space
* fastest thing there is
227
Colour depends on what for eye
Diff wavelengths is diff colours
228
Colour depends on what for eye
Diff wavelengths is diff colours
229
Monocromatic light
Light of a single wavelength and colour
230
Refractive index formula
spped of light in vaccum/speed of light in medium
231
Effect of splitting of light in prism is called
Dispersion
232
Diatomic
Having two atoms
233
Does hcl prevent rust
No
234
Electrolysis is used for
Most reactive
235
Naturally found elements are (more/less reactive than elements found by electrolysis)
Naturally found elements are less reactive than elements found by electrolysis
236
Which is stronger alloy or metal
Alloy is stronger
237
Malleable
Hammered into shape without breaking
238
Ductile
Can be drawn into wires
239
Sonorous
Make a ringing noise when struck
240
When reacting with cold h2o
The more reactive the elemet is the more violent the reaction is
If the element is not reactive, no reaction takes place
241
Why are more reactive metals, harder to extract
They are more stable so they form compunds with strong bonds
242
Soft metal
Sodium
243
Metal that floats on water
Sodium
244
Unreactive metal
Gold
245
Metal oxides
| acids/bases
Bases
246
Metals react to form positive/negative ions
+ ions
247
mgh vs PGH formula
mgh - PE potential energy
pgh - pressure in liq
