100 or so IGCSE Physics things to learn Flashcards
1
Q
What component is this?
A
Variable resistor
2
Q
Electrical hazards include….
A
Frayed cables, damaged sockets, water near sockets and metal objects in sockets
3
Q
Give the unit and unit symbol for
Volume, V
A
metre cubed (m3)
4
Q
The initial linear part of a force-extension graph is linked to what law?
A
Hooke’s Law (Force is directly proportional to extension)
5
Q
What type of radioactive decay is most penetrating?
A
Gamma
6
Q
How does a fuse work
A
When the current goes higher than the value of the fuse it melts. This breaks the circuit and stops current flowing
7
Q
What are the artificial sources of background radiation?
A
Medical sources, fallout from nuclear weapons testing and use, nuclear accidents
8
Q
Define amplitude
A
Amplitude is the maximum displacement above the equilibrium
9
Q
What happens to the resistance of a thermistor as it is heated
A
High temperatures reduces the resistance of a thermistor
10
Q
Comets orbit what? What shapes are their orbits?
A
Comets orbit stars (e.g. the Sun) in elliptical orbits
11
Q
What are the dangers of ionising radiation?
A
Mutation and damage to cells and tissues
12
Q
What are the energy transfers involved with solar cells
A
Nuclear store ⇒ radiated as light ⇒ electrically transferred in wires
13
Q
What equation links;
wave speed, frequency and wave length
A
wave speed = frequency x wave length
14
Q
Describe the motion of gas particles
A
gas particles move in a random fast motion
15
Q
What are the energy transfers involved with nuclear power
A
nuclear ⇒ heating of water increasing its thermal store ⇒ kinetic energy of particles turn a turbine⇒ powering a generator that electrically transfers in wires
16
Q
After two half-lives, how much of an original sample is left?
A
One quarter
17
Q
Give the unit and unit symbol for
Power, P
A
watt (W)
18
Q
The gradient of a velocity-time graph gives
A
Acceleration
19
Q
What are the energy transfers involved with wind power
A
kinetic store of wind, mechanically transfer to turbine ⇒ electrically transferred in wires
20
Q
What makes something an elastic material
A
Material regains original shape once stretching force is removed
21
Q
What type of radioactive decay is most ionising?
A
Alpha
22
Q
In what two ways can radioactive decay be detected?
A
By photographic film and by a Geiger-Müller (GM) Tube
23
Q
How can you prevent heat transfer by radiation?
A
Shiny surfaces are poor emitters. They also refelect the thermal radiation back.
24
Q
Give an example of an AC source and a DC source
A
Mains are an AC source. Batteries are DC sources
25
Our local galaxy is called
The Milky Way
26
What isotope Carbon-14 often used for
radiometric dating; identifying how old something is based on the count rate of the carbon-14
27
When a wave is refracted what two things change
Speed and direction change during refraction
28
# Give the unit and unit symbol for
Length, l
metre (m)
29
What's wrong with -50K as a temperature?
You can't have negative kelvin temperatures, absolute zero (0K) is the coldest temperature possible
30
What part of the EM spectrum has the longest wavelength
Radio has the longest wavelength
31
After three half-lives, how much of an original sample is left?
One eighth
32
# Give the unit and unit symbol for
Moment
newton metre (Nm)
33
How is electricity generated in a generator?
A large coil is spun in a strong magentic field, this causes a force on the electrons and makes them flow producing a current.
34
# Give the unit and unit symbol for
Density, ρ
kilogram per metre cubed (kg/m3)
35
Define the time period of a wave
Time period is how long it takes for a wave to pass a point
36
Factors which affect thinking distance
Speed, awareness (tired, alcohol)
37
What happens when current flows through a resistor
When current flows through a resistor it heats up (this effect is used in kettles and toasters etc.)
38
# Give the unit and unit symbol for
Wavelength, λ
metre (m)
39
How can you increase the amount of voltage which is induced when moving a magnet into a coil?
Stronger magnet, move magnet faster
40
What does work done = energy transferred mean?
If you do 10J of work on a system you transfer 10J of energy to it.
41
The area under a velocity-time graph gives
Distance travelled
42
Waves transfer ……………………………… without transferring ……………………….
Waves transfer energy and information without transferring matter
43
Forces can do what to an object?
Change speed, shape or direction
44
The rate of doing work is also known as?
Power
45
# Give the unit and unit symbol for
Frequency, f
hertz (Hz)
46
# What equation links;
voltage, current and resistance
voltage = current x resistance
47
List the 4 types of energy transfer
List the 4 types of energy transfer
48
What is the easiest way to reduce risk of injury from microwaves, infra red, ultra violet or gamma
Avoid exposure
49
When the angle of incidence is greater than the critical angle light is…
Totally internally reflected
50
After four half-lives, how much of an original sample is left?
One sixteenth
51
# Give the unit and unit symbol for
Mass, m
kilogram (kg)
52
What are the energy transfers involved with solar heating systems
Nuclear store of sun ⇒ heating water to increase thermal store
53
# What equation links;
pressure difference, height, density and g
pressure difference = height x density x g
54
What component is this?
Bulb
55
If a car has 20 000J of kinetic energy, how much work do the brakes have to do to stop the car?
20 000J
56
What is a magnetic field line?
A magnetic field line shows the direction of a magnetic field (N to S). Where lines are close together the field is strong.
57
How would you describe a uniform field (3 marks)
Field lines are straight, parallel and equally spaced in a uniform field
58
How can you visualise the shape of a magnetic field (3 marks)
Place magnet under paper, sprinkle iron filings on top of paper, gently tap paper so filings line up with field lines.
59
Give a danger and use for microwaves
Danger = internal heating of body tissue,
Use = cooking and satellite communications
60
How do gas particles exert pressure on a container
molecules collide with walls of container,
exert a force,
over a given area,
pressure = force / area
61
Name some electrical conductors (low resistance, allow current to easily flow)
Metal, graphite
62
Which way does light bend when it enters a material with a higher refractive index (e.g. air to glass)
Light bends towards the normal when it goes from air to glass
63
# Give the unit and unit symbol for
Pressure, p
pascal, newton per metre (Pa, N/m2)
64
What happens to the current in a circuit when the resistance is decreased?
Current increases as resistance decreases
65
What happens to the current in series circuit as more bulbs are added?
More bulbs in series increases the resistance and decreases the current
66
# What equation links;
average speed, distance and time
speed = distance ÷ time
average speed = total distance ÷ total time
67
# What equation links;
refractive index and critical angle
n = 1 ÷ sin c
refractive index = 1 ÷ sin (critical angle)
68
What materials does convection happen best in and why
Fluids (gases and liquids); particles must be free to move so can't happen in a solid
69
What materials does radiation happen best in and why?
Transparent (see through) materials; thermal radiation can be absorbed by some materials and pass through others.
70
Natural satellites (e.g. moons) and artificial satellites (e.g. Hubble) orbit what?
Planets
71
What are the natural sources of background radiation?
Radon gas, cosmic rays, the ground, food and drink
72
# Give the unit and unit symbol for
Resistance, R
ohm (Ω)
73
What component is this?
Diode
74
What happens to the resistance of an LDR as more light is shone on it?
Bright light reduces the resistance of an LDR
75
A galaxy is made up of…
Billions of stars
76
Describe how thermal energy is transferred by radiation
Thermal radiation is an electromagnetic wave.
77
# What equation links;
efficiency, useful energy output and total energy input
efficiency = useful energy output ÷ total energy input
(also efficiency = useful energy output ÷ total energy output)
78
When a wire is moved through a magnetic field what happens?
A wire moving through a magnet causes a current to flow
79
What are circuit breakers
Circuit breakers break the circuit when the current goes higher than a certain value. Unlike fuses, they can be reset once tripped.
80
When the angle of incidence is less than the critical angle light is…
When the angle is less than the critical angle, light is refracted
81
# Give the unit and unit symbol for
Temperature, T
kelvin (K)
82
# Give the unit and unit symbol for
Area, A
metre squared (m2)
83
What is the role of the control rods in a nuclear reactor?
To control the rate of reaction by absorbing neutrons
84
# What equation links;
charge, current and time
charge = current x time
85
What type of radioactive decay emits a helium nucleus?
Alpha
86
What component is this?
Wire
87
How can you increase the speed of a motor (or volume of a speaker)?
Stronger magnet, more current
88
# What equation links;
gravitational potential energy, mass, g and height
gravitational potential energy = mass x g x height
89
# What equation links;
refractive index, angle of incidence, angle or refraction
n = sin i ÷ sin r
refractive index = sin (angle of incidence) ÷ sin (angle of refraction)
90
Refraction is when a wave………………………..
...bends
91
# What equation links;
weight, mass and gravitational field strength
weight = mass x gravitational field strength
92
What is the relationship between force and extension for a spring
Force is directly proportional to extention (if force doubles extension doubles)
93
List the 8 types of stored energies
Thermal, Chemical, Nuclear, Elastic, Gravitational, Kinetic, Electrostatic, Magnetic
94
What materials does conduction happen best in and why?
Solids; particles are close together so can pass energy quickly. Works best of all in metals due to free electrons.
95
Why do different planets have different values of g (gravitational field strength)
Planets with more mass (e.g. Jupiter) have a higher value of g
96
What is the order of the EM spectrum
Radio, Microwave, Infra-red, Visible, Ultra-violet, X-ray & Gamma
97
What is the frequency range for human hearing
20 Hz - 20 000 Hz
98
What happens to the speed of an object as it falls?
What happens to its drag?
Speed increases (resultant force downwards)
drag increases
99
What is double insulation
Appliances with plastic cases are double insulated; even if live wire comes loose inside, a user can't be shocked
100
# What equation links;
density, mass and volume
density = mass ÷ volume
101
How can you prevent heat transfer by convection?
Trap the fluids (e.g. trapping air in wool). This prevents both conduction and convection.
102
Factors which affect braking distance
Speed, weight of vehicle, quality of brakes and tryes, road surface
103
Explain parallel circuits
Several routes for current to take, allows components to be switched on individually (e.g. lights at home), components get full supply voltage
104
What types of radioactive decay do not change an isotope's mass number?
Beta and Gamma
105
When a gas or liquid is at rest, what can you say about the pressure?
at a given depth, pressure in a fluid at rest acts equally in all directions
106
What is another name for the rate of flow of charge?
Current
107
# Give the unit and unit symbol for
Energy, E
joule (J)
108
Reflection is when a wave…………………………
...bounces off something
109
Give a danger and use for gamma
Danger = cancer, mutation,
Use = sterilising food and medical equipment
110
How can you produce a uniform magnetic field (3 marks)
Place two attracting bar magnet poles (N&S) close together, hold them in place to avoid them touching
111
What type of radioactive decay emits an electron?
Beta
112
The universe is made up of….
Billions of galaxies
113
How can you prevent heat transfer by conduction?
Use insulators (such as air)
114
What is the role of the moderator in a nuclear reactor?
To slow neutrons down so that they can cause new fissions
115
# Give the unit and unit symbol for
Charge, Q
coulomb (C)
116
The gradient of a distance-time graph gives
Speed
117
What type of radioactive decay changes both an isotope's mass number and its atomic number?
Alpha
118
What type of radioactive decay does not emit a particle?
Gamma
119
# What equation links;
work done, force and distance moved
work done = force x distance moved
120
What component is this?
Thermistor
121
What is the mass number?
The total number of protons and neutrons
122
If an object has 100J of gravitational potential energy when on a shelf and falls off, how much kinetic energy does it have just before hitting the floor? What have you assumed?
100J. But we assume there is no air resistance (100% efficient)
123
Give a use for x-rays
looking at the insides of things (medical imaging and other objects)
124
# Give the unit and unit symbol for
Force, F
newton (N)
125
How do you convert from K to C?
What is 300K in °C?
What is 100K in °C?
Subtract 273,
300K-273 = 27 °C,
100K-273 = -173 °C
126
How do you convert from C to K?
What is 20 °C in K?
What is -40 °C in K?
Add 273,
20 °C + 273 = 293 K,
-40 °C + 273 = 233 K
127
When investigating the relationship between pressure and volume what two quatities must you keep constant?
Temperature and mass of gas must be kept constant when investigating pressure and volume
128
What is the principle of conservation of energy
Energy cannot be created or destroyed; only changed from one form to another.
129
How does convection produce wind?
Air is heated, expands, becomes less dense, rises, colder air rushes into the area of low pressure.
130
Give a danger and use for infra red
Danger = skin burns,
Use = cooking and night vision equipment
131
How can you produce more electricity in a generator?
Stronger magnet, spin coil faster
132
Describe a transverse wave and give an example
Transverse waves travel at right angles to the oscillation which caused them. E.g. light, other EM waves, Mexican Waves
133
What part of the EM spectrum has the highest frequency (and energy)
Gamma has the highest frequency
134
Give a danger and use for ultra violet
Danger = blindness and damage to surface cells,
Use = flourescent lamps, security markings
135
Give a use for visible light
Seeing, optical fibres, photography
136
What do the thumb and fingers represent when using Flemming's Left Hand Rule?
thumb = force (direction of movement),
First Finger = Field,
seCond finger = Current
137
When a magnet moves through a coil of wire what happens?
A magnet moving through a coil causes a current to flow
138
# What equation links;
moment, force and perpendicular distance from pivot
moment = force x perpendicular distance from pivot
139
Do isotopes have the same atomic number, or the same mass number?
Atomic number (number of protons)
140
How would you find the volume of a small irregular object (e.g. a pebble)
submerge in water. The volume of water displaced = volume of pebble
141
What happens to the pressure of a gas in a sealed container when you heat it? Why?
Pressure increases when you heat a sealed container of gas,
molecules move faster hitting walls harder and more often,
more force exerted on same area,
pressure increases
142
How can you show current is flowing in a circuit
A bulb or LED will light when a current flows. Or use an ammeter (in series)
143
How can you see the shape **and** direction of a magnetic field
Use plotting compasses
144
# What equation links;
acceleration, change in velocity and time taken
acceleration = change in velocity ÷ time taken
145
How can air molecules move heavy smoke particles (Brownian motion)
lots of tiny, fast moving air molecules exert enough force on a smoke particle to change its direction
146
One Watt is equal to what?
1 watt is 1 joule per second
147
Why does an object reach terminal velocity?
As the speed and drag increase, eventually weight = drag so no resultant force
148
Define wavelength
Wavelength is the distance between two peaks or two troughs
149
What are meters X and Y?
X is a voltmeter (in parallel)
Y is an ammeter (in series)
150
How would you find the volume of a regular object (e.g. a cube of metal)
measure each side (with ruler) and multiply together
151
What component is this?
LDR (light dependent resistor)
152
What type of radioactive decay can be stopped by a sheet of paper?
Alpha
153
Why aren't machines 100% efficient?
Typically some energy is lost to the surroundings as heat.
154
What is the nature of an electric current in a metal conductor?
A flow of negatively charged electrons flowing from the negative side of a battery or power supply
155
What is the difference between Alternating Current (AC) and Direct Current (DC)
DC (direct current) only flows in one direction. AC (alternating current) constantly changes direction.
156
What is the atomic number?
The number of protons
157
What happens to the pressure acting in a fluid as you go deeper?
pressure increases as you go deeper into a fluid
158
What are the energy transfers involved with geothermal power
(nuclear) ⇒ heating of water thermal store increases ⇒ kinetic energy of molecules mechanically driving a turbine ⇒ electrically transferred in wires
159
What are the energy transfers involved with water power
(nuclear) ⇒ heating of water thermal store increases ⇒ kinetic energy of molecules mechanically driving a turbine ⇒ electrically transferred in wires
160
# What equation links;
pressure, force and area
pressure = force ÷ area
161
What happens to particles at absolute zero? What is the pressure? Why?
Paricles stop moving at absolute zero (no KE), pressure is zero as particles are not colliding with walls
162
What happens to the average speed of gas molecules as you heat a gas?
Average speed of gas molecules increases as you heat a gas
163
# Give the unit and unit symbol for
Time, t
second (s)
164
# Give the unit and unit symbol for
Velocity (initial, final), (u,v)
metre per second (m/s)
165
# What equation links;
energy transferred and work done
energy transferred = work done
166
# What equation links;
kinetic energy, mass and speed
kinetic energy = 1/2 x mass x speed2
167
What type of radioactive decay can only be stopped by a few millimetres of aluminium?
Beta
168
Describe how thermal energy is transferred by convection
Hotter regions of fluid expand, become less dense and float on colder regions
169
Describe how thermal energy is transferred by conduction
Particles knock into each other and pass on the energy
170
# Give the unit and unit symbol for
Potential Difference, V
volt (V)
171
Explain series circuits
Only one loop, simple, if one component fails no current flows
172
What component is this?
Diode
173
How do radiators in your house heat a room (hint, not by radiation)
Radiators heat air which rises and produces a convection current. Cold air is drawn into the bottom of the radiator too.
174
# Give the unit and unit symbol for
Radioactive activity, A
becquerel (Bq)
175
What is the critical angle
When ligh hits the boundary at the critical angle the angle of refraction is 90°
176
What type of radioactive decay can only be stopped by a few centimetres of lead?
Gamma
177
What is the force which opposes motion
Friction (e.g. against a road) or drag (e.g. moving through air)
178
What particle do control rods absorb?
Neutrons
179
# Give the unit and unit symbol for
Acceleration, a
metre per second squared (m/s/s, m/s2)
180
Where does an objects weight always act
Through its centre of gravity
181
Planets orbit what? What shape are their orbits?
Planets orbit stars (e.g. the Sun) in circular orbits
182
What is felt when a current-carrying wire is in a magnetic field?
A force is felt when a wire carries a current in a magnetic field
183
What is the efficiency of this machine
useful output energy = 10J
total input energy = 100J
efficiency = 10/100
= 0.1 or 10%
184
Where does the ray go next in each case?
185
# Give the unit and unit symbol for
Electric current, I
amp (A)
186
# What equation links;
force, mass and acceleration
force = mass x acceleration
187
If you double the volume of a sealed container of gas (at a constant temperature) what happens to the presure?
Pressure will halve
188
What is produced around a conductor when electrical current flows?
An electromagentic field is created when current flows
189
Describe a longitudinal wave and give an example
Longitudinal waves travel parallel to the oscillation which caused them. E.g. sound
190
Name some electrical insulators (high resistance, do not allow current to flow)
Plastic, wood, (pure) water
191
What is the law of reflection?
Angle of incidence = Angle of reflection
192
What are the energy transfers involved with fossil fuels
chemical ⇒ thermal ⇒ kinetic ⇒ electrical
193
Give a use for radio
Communictions and broadcast
194
Define frequency
Frequency is the number of waves going past a point per second
195
Only appliances with what sort of case need an Earth wire?
Appliances with metal cases; if the live wire comes loose someone could get a shock without an Earth wire.
196
What type of radioactive decay can be stopped by a few centimetres of air?
Alpha
