Circuit Questions (GCSE Physics)
Practice GCSE Electricity Questions
The following GCSE Physics electricity exam questions have been compiled to support you in your revision. These include electricity questions as well as specific circuit questions.
Practice Question 1
This diagram shows a parallel circuit. The current flowing through the 20 Ω resistor is 0.3A. Work out the current flowing through the 10 Ω and the total voltage of the cell.
The resistance through the 10 Ohm resistor is half of the 20 Ohm
resistor, so current is double = 0.6A. V = IR.
Looking at one branch, V = 0.3 X 20 = 6V
Practice Question 2
This diagram shows a circuit with two identical lamps. Each lamp has a resistance of 3 Ω and the cell is supplying a voltage of 12 V
- When switch P is closed and Q is open, the current in the circuit is 2A and only Lamp B is lit.
- When switches P and Q are both open, the current in the circuit is 2A and both lamps are lit.
- When switch Q is closed and P is open, the current in the circuit is 4A and only Lamp A is lit.
- When switches P and Q are both closed, neither lamp is lit.
Which of the following statements is / are correct?
- False – I = V / R = 12 / 3 = 4A
- True – I = V / R = 12 / 6 = 2A
- True – I = V / R = 12 / 3 = 4A
- True – a short circuit is formed.
Practice Question 3
Which of the following is a unit of voltage?
- ampere / ohm
- (coulomb x ohm) / second
- coulomb / second
- (second x coulomb) / ohm
- ohm / volt
- coulomb / joule
Current = Charge / Time
Voltage = Current x Resistance Substitute current in the V=IR formula.
Practice Question 4
Below are five statements about parallel circuits. Select which statements are false.
- Each branch of a parallel circuit receives the maximum cell voltage.
- Within a branch of a parallel circuit, the current is always the same.
- In a parallel circuit with multiple bulbs, if one breaks none of the other bulbs will be affected.
- The total resistance in parallel circuits is the sum of the individual resistances of all components.
1. True – in a parallel circuit the voltage is not shared, in contrast to a series circuit. Each branch gets the maximum voltage
2. True – each branch of a parallel circuit acts like its own mini series circuit. Different branches can have different currents, but within each branch the current is constant.
3. False – this is incorrect, because only the bulbs in the same branch are affected. In a series circuit, in contrast, one broken lamp affects all the lamps.
4. False – This is incorrect, as the reciprocal of the resistance is the sum of the reciprocals of the individual resistances.
Practice Question 5
The circuit below shows five lamps with identical resistance. Initially switch Q is closed.
Switch Q is now opened. Compared with the brightness from before (when Switch Q was closed), how has the brightness of the four lamps changed?
The correct answer is F.
When Switch Q is closed, the current bypasses A, B, D and E. The pathway through Q is the path of least resistance. The resistance in the circuit is quite low, because only lamp C is involved. This is a series circuit in effect. Therefore lamp C is very bright.
When Switch Q is open, the current is now split between the three branches of the circuit like a normal parallel circuit. All the lamps become lit. A, B, D and E are brighter than before as they now receive current. C is dimmer than before, because the total resistance in the circuit is higher as there are many lamps involved (you don’t need to do a calculation – if more lamps are involved, the resistance will inevitably be higher).
FAQs
A circuit is a closed loop of conducting material, such as metal wire, through which electric current can flow. It is made up of components, such as resistors, capacitors, and batteries, which can affect the flow of current in different ways.
Electric current is the flow of electric charge through a material. In a circuit, electric current flows from the positive terminal of a battery through the components and back to the negative terminal, creating a continuous flow of charge.
Resistance is a measure of a material’s opposition to the flow of electric current. In a circuit, the resistance of the components, such as resistors, affects the flow of electric current by slowing it down. The greater the resistance, the less current will flow through the circuit.
Ohm’s Law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points, and inversely proportional to the resistance between them. This means that in a circuit, the current will increase if the voltage is increased or the resistance is decreased.
Capacitors store electric charge, and inductors store energy in a magnetic field. In a circuit, capacitors can slow down or block the flow of current, while inductors can allow current to continue flowing even when the voltage changes.
A parallel circuit is a circuit in which components are connected parallel to each other, rather than in series. This means that each component has its own separate path for electric current, and the total current in the circuit is equal to the sum of the current flowing through each component.
A series circuit is a circuit in which components are connected in a chain, so that the electric current flows through each component in turn. In a series circuit, the total resistance of the circuit is equal to the sum of the resistance of each component.
A switch is an electrical component that can open or close a circuit, allowing or blocking the flow of electric current. In a circuit, the presence of a switch allows for the control of the flow of current, and can be used to turn a device on or off.
Still got a question? Leave a comment
Leave a comment