1. 1
   A technician tests an electrical component by connecting it to a 9 V supply. The current through the component is measured as 1.5 A.

   (a)

   Calculate the resistance of the component.

   [1 mark]

   • A6 Ω
   • B13.5 Ω
   • C0.17 Ω
   • D10.5 Ω

   (b)

   Which statement correctly describes electric current in a solid metallic conductor?

   [1 mark]

   • AThe rate of flow of positive charge carried by protons
   • BThe rate of flow of negative charge carried by electrons
   • CThe total charge stored in the conductor
   • DThe energy transferred per unit charge

   (c)

   Calculate the charge that flows through the component in 40 s at this current of 1.5 A.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Two identical lamps are connected first in series and then in parallel across the same 6 V battery, to compare how brightly they glow in each arrangement.

   (a)

   In which arrangement is the potential difference across each lamp equal to the full 6 V of the battery?

   [1 mark]

   • ASeries
   • BNeither arrangement
   • CParallel
   • DBoth arrangements

   (b)

   In which arrangement would the lamps be expected to glow more brightly, and why?

   [1 mark]

   • ASeries, because the current is shared equally between the lamps
   • BSeries, because the combined resistance is lower
   • CParallel, because the current through each lamp is halved
   • DParallel, because each lamp has the full battery voltage across it

   (c)

   In the series arrangement, the current is 0.5 A. Calculate the combined resistance of the two lamps in series, given the battery provides 6 V.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A portable electric heater is connected to the 230 V mains supply and draws a current of 8 A while operating.

   (a)

   Calculate the power of the heater.

   [3 marks]

   (b)

   The heater is switched on for 1800 s (30 minutes). Calculate the energy transferred by the heater during this time, giving your answer in kilojoules.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student rubs a plastic (polymer) comb with a dry cloth. Afterwards, the comb attracts small, uncharged pieces of paper. The charged comb is then touched to an isolated metal sphere, transferring charge to it.

   (a)

   Explain, in terms of the movement of electrons, why the plastic comb becomes negatively charged when rubbed with the dry cloth, and why the charged comb attracts the small, uncharged pieces of paper.

   [6 marks]

   (b)

   The charged comb transfers a charge of −8 × 10⁻⁹ C to the metal sphere over a time of 2 × 10⁻³ s. Calculate the average current that flowed during the transfer, and state the direction of conventional current flow during this process.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   A technician connects an unknown resistor to a 20 V supply and records a current of 2 A through it.

   (a)

   Calculate the resistance of the unknown resistor.

   [1 mark]

   • A40 Ω
   • B10 Ω
   • C22 Ω
   • D0.1 Ω

   (b)

   Which statement correctly explains why the potential difference across two components connected in parallel is the same?

   [1 mark]

   • AThey are connected between the same two points in the circuit
   • BThe same current flows through each component
   • CTheir resistances must be equal
   • DCharge is not conserved at the junction between them

   (c)

   Calculate the charge that flows through the resistor in 5 s at this current of 2 A.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   A circuit contains a 4 Ω resistor and an 8 Ω resistor, each connected directly across a 24 V battery in parallel.

   (a)

   What is the potential difference across the 8 Ω resistor?

   [1 mark]

   • A12 V
   • B8 V
   • C3 V
   • D24 V

   (b)

   Which statement correctly compares the currents in the two resistors?

   [1 mark]

   • AThe current in the 4 Ω resistor is smaller than in the 8 Ω resistor
   • BThe currents in the two resistors are equal
   • CThe current in the 4 Ω resistor is greater than in the 8 Ω resistor
   • DThe current cannot be determined from the information given

   (c)

   Calculate the current in the 4 Ω resistor.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   An electric kettle is connected to the 230 V mains supply and has a power rating of 2300 W.

   (a)

   Calculate the current drawn by the kettle when it is operating normally.

   [3 marks]

   (b)

   The kettle is used for 240 s to boil water. Calculate the energy transferred by the kettle during this time, giving your answer in kilojoules.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   Dry powder is transported along a conveyor belt in a flour mill. Friction between the powder and the belt causes charge to build up on ungrounded metal parts of the machinery, creating a risk of sparking. Before an earthing strap is fitted, a potential difference of 40 000 V builds up between the machinery and earth. An engineer then fits an earthing strap of resistance 2 × 10⁵ Ω between the machinery and the ground.

   (a)

   Explain how friction between the powder and the conveyor belt causes charge to build up on the machinery, and explain why this creates a risk of sparking if the machinery is not earthed.

   [6 marks]

   (b)

   Explain how fitting the earthing strap removes the risk of a large charge building up on the machinery, and calculate the initial current that would flow through the strap at the moment it is connected, given the 40 000 V potential difference and the strap's resistance of 2 × 10⁵ Ω.

   [6 marks]

   Total for question 8: 12 marks

End of questions