Edexcel GCSE Combined Science: Physics: Electricity and Circuits
6 exam-style questions with full mark schemes and model answers. Write your own answer and the AI examiner marks it against the mark scheme.
Components in a circuit can be connected in series or in parallel. A string of lamps for decorating a room can be wired either way.
Compare how lamps behave when they are connected in series with how they behave when connected in parallel. In your answer you should refer to the current, the potential difference (voltage) across each lamp, and what happens to the other lamps if one lamp breaks. (6 marks)
A student investigates how the current through a fixed resistor depends on the potential difference across it. They record the current at several values of potential difference. The results are shown below.
| Potential difference / V | Current / A |
|---|---|
| 0 | 0 |
| 2.0 | 0.10 |
| 4.0 | 0.20 |
| 6.0 | 0.30 |
| 8.0 | 0.40 |
(a) Using the readings at 6.0 V, calculate the resistance of the fixed resistor. Use the equation V=IR. Show your working and give the unit. (2 marks)
(b) The results show that the current is directly proportional to the potential difference. State what this tells you about the resistance of the fixed resistor as the potential difference changes, and name this type of component. (2 marks)
An electric heater is connected to the mains supply. A charge of 600 C flows through the heater in a time of 120 s.
(a) Calculate the current in the heater. Use the equation Q=It. Show your working and give the unit. (2 marks)
(b) Define what is meant by the electric current in a circuit. (1 mark)
An electric kettle is connected to the 230 V mains supply. When it is switched on, a current of 9.0 A flows through its heating element.
(a) Calculate the power of the kettle. Use the equation P=IV. Show your working and give the unit. (2 marks)
(b) The kettle is left running for 180 s. Calculate the energy transferred to the kettle in this time. Use the equation E=IVt (or E=Pt). (1 mark)
A thermistor is a component used in temperature-sensing circuits. Its resistance depends on temperature.
Describe and explain what happens to the resistance of a thermistor as its temperature increases. (2 marks)
Mains electricity in the United Kingdom is supplied as an alternating current (a.c.).
State what is meant by an alternating current. (1 mark)