2019

• correct way to connect an ammeter and a voltmeter into the circuit

  ammeter-in series with the resistor

  voltmeter-in parallel with the resistor
• increase resistance

  decrease current
• changing the circuit to give negative values for current and pd

  Reverse the connections to the cell
• relationship btw current and pd for a resistor at constant temp

  directly proportional
• equation linking to current,pd,resistance

  pd=current $\times$resistance
• what is meant by a non-renewable energy resource

  an energy source that can't be replenished as it is used
• explain the difference between direct and alternating pd

  -Direct PD is always in the same direction

  -alternating PD changes direction
• Low resistance is better why than high resistance

  -lower pd across the cable

  -so therefore more efficient
• Explain how the current in the thermistor changed.

  Answer:

  • the current increased
  • because the resistance of the thermistor decreased
• Question:Explain how the potential difference across the resistor and the lamp will change when the switch is closed.

  Answer:The resistor

  • the potential difference across the resistor becomes 0 V
  • because there is a short circuit across the resistor

  The lamp

  • the potential difference across the lamp increases
  • because the current increases
• Why is it difficult to detect gamma radiation?

  Answer:

  • gamma is only weakly ionising
• What happens to the mass number and the charge of the nucleus when gamma radiation is emitted?

  Answer

  Mass number Charge

  Stays the same

  Stays the same ✔
• Explain why the count rate was less than the activity of the sample of lanthanum-140.

  Answer:

  • the radiation spreads out in all directions
  • only some of the radiation goes into the GM tube
• Explain why the teacher stood as far away from the apparatus as possible.

  Answer:

  • to reduce the amount of radiation received
  • because radiation increases the risk of cancer or genetic mutation
• Explain the changes in the arrangement and movement of the particles of the argon as the temperature of the air decreased.

  Answer:Cooling:

  • as the argon cools the particles slow down
  • particles in a liquid move slower than particles in a gas
  • particles in a solid move slower than particles in a liquid
  • as the liquid/solid cools the particles get closer together
  • as the liquid/solid cools the density increases

  Gas to liquid:

  • particles change from being spread apart to touching each other
  • particles will collide with other particles more often and will change direction more often

  Liquid to solid:

  • particles change from a random arrangement to a regular pattern
  • particles change from moving freely to fixed positions
  • particles change from moving randomly to vibrating