Electricity

Figure 9 shows a circuit diagram. In which position could a switch be placed so that both lamps can be switched on or off at the same time?

Draw the circuit symbol for a switch in the box below.

In 30 seconds, 24 coulombs of charge flow through the battery. Calculate the current in the battery. Use the equation: current = charge flow / time

There is a potential difference of 3.6 V across the battery. Calculate the energy transferred by the battery when 60 coulombs of charge flows through the battery. Use the equation: energy transferred = charge flow × potential difference

A student built Circuit X and Circuit Y shown in Figure 10. The components used in each circuit were identical. How would the reading on the ammeter in Circuit Y compare to the reading on the ammeter in Circuit X?

How does the total resistance of Circuit Y compare with the total resistance of Circuit X?

The student built another circuit which is shown in Figure 11. Write down the equation which links current, potential difference and resistance.

There is a potential difference of 3.6 V across the lamp in Figure 11. The current through the lamp is 0.80 A. Calculate the resistance of the lamp.

A student investigated how the length of a wire affects its resistance at a constant temperature. The student used a power supply, an ammeter, a voltmeter, a switch, a resistor wire attached to a ruler, and connecting leads. Describe a method the student could have used to collect the data needed to plot a graph of resistance against the length of the wire.

Which graph shows the relationship between the resistance of a wire at constant temperature and its length?

The student used a cell that had a potential difference of 1.50 V. Explain why the cell was **not** an electrical hazard to the student in the investigation.

A student with long hair touches the negatively charged metal dome of a static electricity generator (a Van de Graaff generator). Her hair stands on end. Explain why the student's hair stands up on end.

The charged metal dome creates an electric field. What is an electric field?

How does the electric field strength vary as the distance from the charged metal dome increases?

When an earthed conductor is moved towards the negatively charged metal dome, there is a spark between the dome and the earthed conductor. The spark transfers 0.60 J of energy, and 2.0 μC of charge is transferred from the dome to the earthed conductor. Calculate the potential difference between the metal dome and the earthed conductor. Use the Physics Equations Sheet.

A vending machine is connected to the mains electricity supply. What is the frequency and the potential difference of the mains electricity supply in the UK?

The vending machine identifies the value of the coin by measuring the resistance of the coin. The power dissipated by the coin is 340 mW when the current in the coin is 0.75 A. Calculate the resistance of the coin. Use the Physics Equations Sheet.

Coins that are dirty are **not** recognised by the vending machine. Suggest **one** reason why.

Figure 8 shows part of a different circuit that is used to monitor the temperature inside the vending machine. The circuit symbol for a thermistor has not been included. Draw the circuit symbol for a thermistor in the box below.