Physics GCSE combined

• potential difference (V) is measured in volts, V
• What happens to the resistance if a bulb glows brighter?


  It has increased
• What is it called when potential difference is not directly proportional?


  Non ohmic conductor
• How do you measure current?


  Ammeter- (amps)
• What does the green wire do in a plug?


  Called the earth wire, it is a safety precaution with a potential of 0 incase another wire busts.
• What does the brown wire do in a plug?


  It is the live wire which powers the plug with a potential of 230V
• What does the blue wire do in a plug?


  It is neutral, completing the circuit which has a potential of 0V.
• What will happen if someone touches the live wire when it is loose?


  They will recieve an electric shock.
• Why do you need to switch a circuit off inbetween readings?


  So it doesnt overheat- therefore more accurate results.
• What does a step down transformer do at a power plant?


  Decreases potential difference for homes, factories etc as they are not able to handle the power otherwise.
• What is irridation?


  Can destroy organisms on food that may cause illness. (Gamma radiation- they will NOT become radioactive)
• What is radioactive contamination?


  Unwanted presence of radioactive particles on materials. -decay and emit radiation
• What is activity of background radiation measured in?


  Becquerels (Bq)
• What is radiation dose measured in?


  Sieverts (Su)
• What is nuclear fission?


  Is the splitting of a large and unstable nucleus into 2 smaller nuclei. This process releases large amounts of energy -can occur in nature
• What is a transverse wave?


  Particles in a transverse wave oscillate (vibrate) perpendicular to the direction of energy transfer

  -water waves

  -mexican waves
• What is a longitudinal wave?


  A longitudinal wave is a wave in which the particles of the medium vibrate parallel to the direction of energy transfer

  -sound waves
• What is specific latent heat?

  The energy required per kg to change the state of a substance
• What is inertia?

  The tendency of an object to continue in its current state. If moving, it will want to remain moving. if stationery, it will remain stationary
• What is the fuse in the plug?

  Thin wire that melts if the current gets too high.
• What is refraction?


  The change in a speed of wave due to a change in medium. If going from less dense to more dense, it will move closer to the normal
• What is specific heat capacity?

  The energy required to change the temperature of 1kg of a substance by 1°C
• What is conduction?


  Vibrating particles transfer energy to neighbouring particles

  In solids, particles are closer together so therefore more collisions

  "Thermal conductivity" is how well objects transfer energy by conduction
• What is the conservation of energy? 


  Energy can only be transferred, never created or destroyed.

  Unwanted energy transfers can be prevented using lubricant.
• What is work done?

  Whenever energy is transferred to one store from another
• conductor


  A conductor is a material that allows internal (thermal) energy to be transmitted through it easily.
• insulator


  An insulator is a material that will not allow the easy flow of energy.
• to test the thermal conductivity of different materials.

  1. Place a small beaker into a larger beaker.
  2. Fill the small beaker with hot water from a kettle.
  3. Put a piece of cardboard over the beakers as a lid. The lid should have a hole suitable for a thermometer.
  4. Place a thermometer into the smaller beaker through the hole.
  5. Record the temperature of the water in the small beaker and start the stopwatch.
  6. Record the temperature of the water every 2 minutes for 20 minutes.
  7. Repeat steps 1-6, each time packing the space between the large beaker and small beaker with the chosen insulating material.
• What is newtons 1st law?

  an object at rest stays at rest, and an object in motion stays in motion at a constant speed and in a straight line unless acted upon by a force.
• What is Newtons 2nd law?

  inertial mass is a measure of how difficult it is to change the velocity of an object
• What is Newtons 3rd law?

  if an object A exerts a force on object B, then object B will exert an equal but opposite force on object A
• The skateboard moves backwards as the skateboarder jumps forwards. Explain using momentum

  When the skateboard was stationary, the momentum was 0. This will also be the same after the collision as momentum always stays the same. When an equal but opposite force is exerted onto it, jumping forward, the momentum of the skateboard becomes positive and the skateboarder negative
• What happens to the velocity of a stone when it falls through the air?

  Velocity is a vector that requires direction and magnitude. When the stone falls, magnitude increases and direction remains constant
• As the stone moves through the water, the stone slows to a constant velocity. Explain why.

  -drag is greater than weight

  -so there is a resultant force acting in the opposite direction to the velocity, causinf deceleration

  -velocity decreases as drag increases until drag is equal to weight so velocity is constant
• What is weight measured in?

  newtons
• Explain how using the step up transformers make the network efficient

  Increases potential difference

  Current is reduced, so more useful energy is transferred + less energy loss to the surroundings
• What electrical component is used to monitor the temp of vegetable oil?

  Thermistor
• Explain how a change in density of steam is caused by a change in the arrangement of particles

  Particles spread out

  So steam takes up greater volume

  Density = mass / volume so density increases
• What is the motor effect?

  When a conductor carrying a current is placed in the magnetic field of a magnet, the magnet and the conductor exert a force on eachother
• What happens to temperature when you melt ice cubes?

  It stays the same