100 or so IGCSE Physics things to learn Flashcards
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
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
What happens to the resistance of a thermistor as it is heated
High temperatures reduces the resistance of a thermistor
Give the unit and unit symbol for
Power, P
watt (W)
Give the unit and unit symbol for
Density, ρ
kilogram per metre cubed (kg/m3)
What component is this?
Bulb
What does work done = energy transferred mean?
If you do 10J of work on a system you transfer 10J of energy to it.
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.
What equation links;
weight, mass and gravitational field strength
weight = mass x gravitational field strength
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
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
Give a use for x-rays
looking at the insides of things (medical imaging and other objects)
Give the unit and unit symbol for
Acceleration, a
metre per second squared (m/s/s, m/s2)
How would you find the volume of a regular object (e.g. a cube of metal)
measure each side (with ruler) and multiply together
What equation links;
pressure, force and area
pressure = force ÷ area
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
Describe a longitudinal wave and give an example
Longitudinal waves travel parallel to the oscillation which caused them. E.g. sound
Give a use for radio
Communictions and broadcast
What are the energy transfers involved with nuclear power
nuclear ⇒ thermal ⇒ kinetic ⇒ electrical
Give a danger and use for microwaves
Danger = internal heating of body tissue,
Use = cooking and satellite communications
What equation links;
charge, current and time
charge = current x time
Give a danger and use for ultra violet
Danger = blindness and damage to surface cells,
Use = flourescent lamps, security markings
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.
What happens to the current in a circuit when the resistance is decreased?
Current increases as resistance decreases
The gradient of a velocity-time graph gives
Acceleration
The gradient of a distance-time graph gives
Speed
Explain series circuits
Only one loop, simple, if one component fails no current flows
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)
The universe is made up of….
Billions of galaxies
What equation links;
acceleration, change in velocity and time taken
acceleration = change in velocity ÷ time taken
Define the time period of a wave
Time period is how long it takes for a wave to pass a point
What equation links;
work done, force and distance moved
work done = force x distance moved
What is the order of the EM spectrum
Radio, Microwave, Infra-red, Visible, Ultra-violet, X-ray & Gamma
When a wave is refracted what two things change
Speed and direction change during refraction
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.
What equation links;
moment, force and perpendicular distance from pivot
moment = force x perpendicular distance from pivot
Give the unit and unit symbol for
Charge, Q
coulomb (C)
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
Give the unit and unit symbol for
Potential Difference, V
volt (V)
What component is this?
Thermistor
What is the force which opposes motion
Friction (e.g. against a road) or drag (e.g. moving through air)
Give the unit and unit symbol for
Wavelength, λ
metre (m)
Factors which affect braking distance
Speed, weight of vehicle, quality of brakes and tryes, road surface
Give the unit and unit symbol for
Pressure, p
pascal, newton per metre (Pa, N/m2)
What equation links;
wave speed, frequency and wave length
wave speed = frequency x wave length
What are the energy transfers involved with water power
gravitational ⇒ kinetic ⇒ electric
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
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.
How does convection produce wind?
Air is heated, expands, becomes less dense, rises, colder air rushes into the area of low pressure.
What is the relationship between force and extension for a spring
Force is directly proportional to extention (if force doubles extension doubles)
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
What makes something an elastic material
Material regains original shape once stretching force is removed
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
Describe how thermal energy is transferred by radiation
Thermal radiation is an electromagnetic wave.
What is the frequency range for human hearing
20 Hz - 20 000 Hz
The initial linear part of a force-extension graph is linked to what law?
Hooke’s Law (Force is directly proportional to extension)
Our local galaxy is called
The Milky Way
What component is this?
LDR (light dependent resistor)
When the angle of incidence is greater than the critical angle light is…
Totally internally reflected
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.)
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.
Why does an object reach terminal velocity?
As the speed and drag increase, eventually weight = drag so no resultant force