100 or so IGCSE Physics things to learn Flashcards
What component is this?
Variable resistor
Electrical hazards include….
Frayed cables, damaged sockets, water near sockets and metal objects in sockets
How many alpha-particles take this path?
What does this show?
Some of the particles take this path.
It shows there is a charged region
Give the unit and unit symbol for
Volume, V
metre cubed (m3)
The initial linear part of a force-extension graph is linked to what law?
Hooke’s Law (Force is directly proportional to extension)
What type of radioactive decay is most penetrating?
Gamma
How does a fuse work
When the current goes higher than the value of the fuse it melts. This breaks the circuit and stops current flowing
What are the artificial sources of background radiation?
Medical sources, fallout from nuclear weapons testing and use, nuclear accidents
Define amplitude
Amplitude is the maximum displacement above the equilibrium
What happens to the resistance of a thermistor as it is heated
High temperatures reduces the resistance of a thermistor
Comets orbit what? What shapes are their orbits?
Comets orbit stars (e.g. the Sun) in elliptical orbits
What are the dangers of ionising radiation?
Mutation and damage to cells and tissues
What are the energy transfers involved with solar cells
light ⇒ electrical
What equation links;
wave speed, frequency and wave length
wave speed = frequency x wave length
Describe the motion of gas particles
gas particles move in a random fast motion
What are the energy transfers involved with nuclear power
nuclear ⇒ thermal ⇒ kinetic ⇒ electrical
After two half-lives, how much of an original sample is left?
One quarter
Give the unit and unit symbol for
Power, P
watt (W)
Why is the image in a mirror virtual?
The image in a mirror can’t be projected onto a screen
The gradient of a velocity-time graph gives
Acceleration
What are the energy transfers involved with wind power
kinetic ⇒ electric
What makes something an elastic material
Material regains original shape once stretching force is removed
What type of radioactive decay is most ionising?
Alpha
In what two ways can radioactive decay be detected?
By photographic film and by a Geiger-Müller (GM) Tube
How can you prevent heat transfer by radiation?
Shiny surfaces are poor emitters. They also refelect the thermal radiation back.
Give an example of an AC source and a DC source
Mains are an AC source. Batteries are DC sources
Our local galaxy is called
The Milky Way
What isotope Carbon-14 often used for
radiometric dating; identifying how old something is based on the count rate of the carbon-14
When a wave is refracted what two things change
Speed and direction change during refraction
Give the unit and unit symbol for
Length, l
metre (m)
What’s wrong with -50K as a temperature?
You can’t have negative kelvin temperatures, absolute zero (0K) is the coldest temperature possible
What part of the EM spectrum has the longest wavelength
Radio has the longest wavelength
After three half-lives, how much of an original sample is left?
One eighth
Give the unit and unit symbol for
Moment
newton metre (Nm)
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.
Give the unit and unit symbol for
Density, ρ
kilogram per metre cubed (kg/m3)
Define the time period of a wave
Time period is how long it takes for a wave to pass a point
Factors which affect thinking distance
Speed, awareness (tired, alcohol)
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.)
Give the unit and unit symbol for
Wavelength, λ
metre (m)
How can you increase the amount of voltage which is induced when moving a magnet into a coil?
Stronger magnet, move magnet faster
What does work done = energy transferred mean?
If you do 10J of work on a system you transfer 10J of energy to it.
The area under a velocity-time graph gives
Distance travelled
Waves transfer ……………………………… without transferring ……………………….
Waves transfer energy and information without transferring matter
Forces can do what to an object?
Change speed, shape or direction
The rate of doing work is also known as?
Power
Give the unit and unit symbol for
Frequency, f
hertz (Hz)
What equation links;
voltage, current and resistance
voltage = current x resistance
List the 5 types of non stored energies
Light, sound, thermal, kinetic, electrical
What is the easiest way to reduce risk of injury from microwaves, infra red, ultra violet or gamma
Avoid exposure
When the angle of incidence is greater than the critical angle light is…
Totally internally reflected
After four half-lives, how much of an original sample is left?
One sixteenth
Give the unit and unit symbol for
Mass, m
kilogram (kg)
What are the energy transfers involved with solar heating systems
thermal ⇒ themal
What equation links;
pressure difference, height, density and g
pressure difference = height x density x g
What component is this?
Bulb
If a car has 20 000J of kinetic energy, how much work do the brakes have to do to stop the car?
20 000J
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.
How would you describe a uniform field (3 marks)
Field lines are straight, parallel and equally spaced in a uniform field
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.
Give a danger and use for microwaves
Danger = internal heating of body tissue,
Use = cooking and satellite communications
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
Name some electrical conductors (low resistance, allow current to easily flow)
Metal, graphite
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
Give the unit and unit symbol for
Pressure, p
pascal, newton per metre (Pa, N/m2)
What happens to the current in a circuit when the resistance is decreased?
Current increases as resistance decreases
What happens to the current in series circuit as more bulbs are added?
More bulbs in series increases the resistance and decreases the current
What equation links;
average speed, distance and time
speed = distance ÷ time
average speed = total distance ÷ total time
What equation links;
refractive index and critical angle
n = 1 ÷ sin c
refractive index = 1 ÷ sin (critical angle)
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
How many alpha-particles take this path?
What does this show?
Very few alpha particles take this path.
It shows there is a central positivley charged region which is very tiny and very dense.
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.
Natural satellites (e.g. moons) and artificial satellites (e.g. Hubble) orbit what?
Planets
What are the natural sources of background radiation?
Radon gas, cosmic rays, the ground, food and drink
Give the unit and unit symbol for
Resistance, R
ohm (Ω)
What component is this?
Diode
What happens to the resistance of an LDR as more light is shone on it?
Bright light reduces the resistance of an LDR
A galaxy is made up of…
Billions of stars
Describe how thermal energy is transferred by radiation
Thermal radiation is an electromagnetic wave.
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)
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
What component is this?
Wire
What is the relationship between force and extension for a spring
Force is directly proportional to extention (if force doubles extension doubles)
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
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
What component is this?
Thermistor
How many alpha-particles take this path?
What does this show?
Most alpha particles take this path.
It shows most of the atom is empty space
Define wavelength
Wavelength is the distance between two peaks or two troughs
What are meters X and Y?
X is a voltmeter (in parallel)
Y is an ammeter (in series)
What component is this?
LDR (light dependent resistor)
Explain series circuits
Only one loop, simple, if one component fails no current flows
What component is this?
Diode
What is the critical angle
When ligh hits the boundary at the critical angle the angle of refraction is 90°
What is the efficiency of this machine
useful output energy = 10J
total input energy = 100J
efficiency = 10/100
= 0.1 or 10%
Where does the ray go next in each case?
What is the law of reflection?
Angle of incidence = Angle of reflection
