GCSE Physics Revision
Forces and Motion
Can you explain each statement or do you need to do more work?
Motion
1. speed = distance travelled/time taken and has units of metres per second2. the features of a distance-time graph e.g. when a body is stationary or moving with a steady speed
3. the features of a velocity-time graph e.g. when a body is moving with constant velocity or constant acceleration
4. acceleration = (v-u)/t and has units of metre per second squared (m/s2)
5. calculate the gradient of a distance-time graph and know that it represents velocity
6. calculate the gradient of a velocity-time graph and know that it represents acceleration
7. the area under a velocity-time graph gives the distance travelled
Forces and Acceleration
8. the forces acting on an object may balance, e.g. when an object rests on a surface9. whenever two bodies interact the forces they exert on each other are equal and opposite
10. balanced forces have no effect on the movement of a body
11. unbalanced forces will effect the movement of a body
12. A Newton is the force needed to give 1 kg an acceleration of 1 m/s 2
13. resultant force = mass x acceleration
Friction
14. friction acts when an object moves through air or water or when solids slide across each other15. when friction can be useful e.g. in braking vehicles
16. the link between speed and braking distance
17. factors controlling the stopping distance of a vehicle including reaction time
18. the faster an object moves the greater the force of friction
19. when a vehicle has a steady speed the frictional forces balance the driving force
20. terminal velocity
GCSE Physics Revision
Further Forces (separate science)
Can you explain each statement or do you need to do more work?
Moments and Centre of Mass
1. The centre of mass (or centre of gravity) is the point at which all the mass of the body appears to act2. For a symmetrical object the centre of mass lies along the axis of symmetry
3. a suspended object comes to rest with its centre of mass (gravity) directly below the point of suspension
4. I know how to find the centre of mass of a thin sheet
5. if the line of action of the weight lies outside the base an object will tend to fall over
6. Moments: if a force is applied at a distance form the pivot it has a turning effect called a moment
7. the turning effect is increased by increasing the force
8. the turning effect is increased by increasing the perpendicular distance between the line of action of the force and the pivot
9. moment= force x perpendicular distance between the line of action and the pivot
10. if an object is not turning, the total clockwise moments must be equal to the total anti-clockwise moments
Momentum
11. Momentum depends on mass and velocity and is a vector12. Momentum = mass x velocity
13. momentum has units of kg m /s
14. when an object collides with another the two objects exert a force on each other which is equal in size but opposite in direction
15. in a collision or explosion momentum is conserved, i.e. momentum before = momentum after
16. in a collision the total kinetic energy (KE) after the collision is less than the total KE before the collision
17. elastic collisions are those involving no overall change in kinetic energy
18. when a force acts a change in momentum occurs
19. force = change in momentum / time
Circular Motion
20. if an object is moving in a circle at a steady speed the direction of its motion is constantly changing21. a (centripetal) force acts towards the centre of the circle
22. the centripetal force is increased if the mass is increased
23. the centripetal force is increased if the speed is increased
24. the centripetal force is increased if the radius is decreased
GCSE Physics Revision
Introductory Electricity
Can you explain each statement or do you need to do more work?
Potential difference in Circuits
1. potential difference is measured in volts (V) using a voltmeter in parallel with the component2. current is measured in amps (A) using a ammeter in series with the component
3. A bigger current flows through a component, when there is a greater potential difference over it.
4. what resistance is, and that it is measured in ohms (Ω).
5. potential difference = current x resistance V = i R
6. the features of the current-voltage graphs for a resistor at constant temp, a filament lamp and a diode.
7. the rules for current and potential difference in both series and parallel circuits.
8. how to draw circuit diagrams using the correct symbols for: switches; cells; batteries; diode; resistor; variable resistor; lamp; fuse; voltmeter; ammeter; thermistor; LDR.
9. how an LDR’s resistance varies w.r.t. light intensity
10. how an thermistors ’s resistance varies w.r.t. temperature
Energy in Circuits
11. current is the flow of charge.12. When current is flowing energy is transferred from the cell to the components in the circuit.
13. when current flows through a resistor, electrical energy is transferred as heat.
14. power has the units of watts (W). 1W = 1 Joule every second
15. power = current x potential difference P = i V
16. charge is measured in coulombs (C) and has the symbol Q
17. energy transferred = potential difference x charge E = VQ
18. charge = current x time Q = i t
Mains Electricity
19. how to wire a plug, why the plug and cable are made of the materials they are.20. UK mains voltage is ≈230V, is a.c. with a frequency of 50Hz and can kill if misused.
21. cells and batteries supply d.c.
22. be able to recognise and compare the oscilloscope traces of d.c. and a.c. voltages.
23. why do we use fuses and circuit breakers, and how they work.
The cost of electricity
24. Electricity is used as it is easy to transform it into other forms.25. energy transferred = power x time E = P t
26. Energy transferred can be measured in either joules (J) or kilowatt-hours (kWh)
· Joules if power is in watts and time is in seconds
· Kilowatt-hours if power is in kilowatts and time is in hours
27. 1 kilowatt-hour = 1 unit of electricity
28. total cost = number of units x cost per unit
GCSE Revision
Static Electricity & Electrolysis
Can you explain each statement or do you need to do more work?
Electric Charge
1. Electrons have a negative charge.2. Protons and therefore nuclei have a positive charge.
3. Electrons can move, while nuclei in solids are fixed in place.
4. When certain different insulators are rubbed, electrons can be knocked off one and onto the other.
5. Objects which gain electrons become negatively charged.
6. Objects which lose electrons become positively charged.
7. Like charges repel, opposite charges attract.
8. How charged objects can attract small objects with induced charges.
Uses of Static Electricity
9. How a photocopier works.10. How an electrostatic smoke precipitator works.
11. Be able to explain of other uses such as ink jet printer and spray painting.
Hazards of Static electricity
12. The greater the charge on an isolated object then the greater the potential difference between it and earth.13. If the potential difference is great enough a spark may jump to earth, this is called arcing
14. How static electricity can be dangerous, and what precautions can be taken to ensure a safe discharge. For example:
· Refuelling aeroplanes
· Pumping fuel through insulator pipes
· Dust extraction
Electrolysis
15. In solids current is a flow of electrons, but current is simply the flow of charge.16. Metals are good conductors because they have some electrons that can move freely through out the metal structure.
17. Ionic compounds are made up of charged particles called ions.
18. When ionic compounds are dissolved or melted then the ions are free to move.
19. Current is able to flow if a potential difference is placed across the solution/liquid. This is due to the ions moving to the oppositely charged electrodes.
20. Simpler substances are released at the electrodes.
1. The mass/volume of the substance deposited is proportional to
· Current
· the time for which the current flows. / 2.
GCSE Physics Revision
Energy Resources and Energy Transfer
Can you explain each statement or do you need to do more work?
Heat Transfer
1. Heat energy travels from places of high temperature to low temperature in 3 ways:· Conduction in solids, metals are best due to free electrons and high density
· Convection in fluids, particles become more energetic so density changes and the less dense fluid rises
· Radiation, energy transfer by electromagnetic waves
2. The heat we feel from hot objects is infra-red radiation, hotter objects give off more.
3. Dark matt surfaces are better absorbers than shiny light surfaces.
4. Shiny light surfaces are better reflectors than dark matt surfaces.
5. Heat energy can be lost through buildings, wasting energy and money.
6. Energy wastage can be reduced by some simple cost effective methods
Energy Resources
7. Most of our energy comes from burning fuels to generate electricity.8. Supplies of fossil fuels and nuclear fuels are limited. They are non-renewable.
9. Energy can also be obtained from renewable resources such as:
· sunlight
· the wind
· waves
· running water, from a high place to a low place
· tides
· geothermal
· wood
10. Power stations use steam to drive turbines which generate electricity.
11. Fuels are burned to generate steam, this produces CO2 and SO2 which contribute to the greenhouse effect and acid rain.
12. Nuclear power stations don’t produce harmful gases but do produce radioactive waste. Are only dangerous if there is an accident.
13. Renewable sources don’t have the same problems with waste products but do have other problems with visual and noise pollution and flooding of land.
14. Fossil fuels can be started up and used at any time, they are reliable.
15. Some renewable energy sources are dependent on environmental factors such as the amount of light or wind, or height of tide.
16. These factors plus others such as costs of fuel, setting up, demand and decommissioning must be compared.
Work, Energy and Power and Efficiency
17. When a force moves an object work is done, energy is transferred.Work Done = Energy Transferred
18. Work Done = Force x Distance Moved (in direction of force) WD = F x d
19. Power = Energy Transferred every second P = E / t
20. Lifting an object increases its Gravitational Potential Energy GPE = m x g x h
21. Elastic potential energy is the energy stored inside an elastic object when deformed.
22. Any transfer involves some heat loss to the surroundings, waste energy.
23. Efficiency is a measure of how much energy is wasted (Useful Energy Out/Energy in)
GCSE Physics Revision
Electromagnetic forces and electromagnetic induction (Co-ordinated)
Can you explain each statement or do you need to do more work?
1. A coil of wire acts like a bar magnet when an electric current flows through it2. A wire carrying a current in a magnetic field may experience the motor effect
3. A d.c. motor uses electromagnetic forces
4. A circuit breaker uses electromagnetic effects
5. Electricity can be made by electromagnetic induction
6. An electric current is induced when a magnet is moved into a coil
7. There are at least three ways of increasing the size of the induced voltage in a coil
8. A generator produces alternating current
9. An alternating current can be shown on a CRO
10. Brush contacts and slips rings are used in a generator
11. Transformers are used to change the voltage of an a.c. supply
12. The national grid uses transformers to step up and step down voltages
13. A transformer works by using electromagnetic induction
14. The transformer equation can be used to predict the output voltage
15. One job of transformers is to reduce power losses in the power lines of the national grid
GCSE Physics Revision
Light – Waves
Can you explain each statement or do you need to do more work?
Wave Behaviour
1. We can observe waves travelling along ropes or springs or on the surface of water2. The amplitude is the maximum displacement
3. The distance between two maxima or minima on the wave is called the wavelength
4. The number of waves per second is called the frequency and has units of Hertz (Hz)
5. Learn this equation wave speed (m/s)=frequency(Hz) x wavelength(m)
6. Waves transfer energy from their source without transferring matter
7. Waves travelling across the surface of water can be refracted
8. Refraction is caused by waves changing speed as they travel from one medium into another (or as the depth of the water changes)
9. Refraction involves a change in direction unless the waves are travelling along a normal
10. When a ray of light is refracted at the boundary between two media some of the light is also reflected
11. If the angle of incidence is greater than the critical angle total internal reflection takes place.
12. Light travels through bent optical fibres by total internal reflection
13. Light can undergo total internal reflection in prisms
14. In transverse waves the disturbance is at right angles to the direction of travel of the wave
15. Light waves are traverse waves and can travel through a vacuum
16. In diffraction, waves spread out as they pass through a gap or around an obstacle
17. Diffraction allows radio signals to be received in the shadow of hills
18. Longer wavelength waves are more strongly diffracted
The Electromagnetic Spectrum