Practise Standard circuit diagram symbols. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy3 marks
(a) Which component allows current to flow in one direction only, and also emits light? Tick (✓) one box.[1]
Diode
LED
Resistor
Thermistor
(b) Which two components have a resistance that changes with the surrounding conditions (light or temperature)? Tick (✓) two boxes.[2]
LDR
Fuse
Thermistor
Switch
Show the answer and mark scheme
(a)Answer: LED
(b)Answer: LDR; Thermistor
Question 2Medium4 marks
A technician describes a circuit: a battery is connected in series with a switch, a fuse, a resistor and an LED. The LED is connected so that it lights when the switch is closed.
Draw a circuit diagram for this circuit, using the correct circuit symbols. Draw the battery with its positive terminal at the top.[4]
Show the answer and mark scheme
Answer: A single series loop containing a battery (positive terminal at the top), a switch, a fuse, a resistor and an LED, with the LED drawn so that conventional current from the positive terminal flows through it in its forward direction.
battery drawn with the correct symbol (two or more cells, each a long and a short line), with its positive terminal (long line) at the top
switch and fuse drawn with the correct symbols, in series with the battery in a single complete loop
resistor drawn as a rectangle, in series with the LED
LED drawn with the correct symbol (diode symbol with two arrows pointing away), pointing in the direction of the conventional current from the positive terminal
Question 3Hard6 marks
A student wants to build a warning circuit for a motor that may overheat. The circuit contains a battery, a switch, a thermistor, a fixed resistor and an LED, all connected in series. The LED should become noticeably brighter as the temperature of the thermistor increases.
Draw a circuit diagram for this circuit, using the correct circuit symbols, and explain how the circuit works and the purpose of each component.[6]
Show the answer and mark scheme
Answer: A series loop of battery, switch, thermistor, fixed resistor and LED, drawn with correct symbols and the LED pointing in the direction of the conventional current; the switch turns the circuit on and off; the fixed resistor limits the current to protect the LED; as the thermistor warms its resistance falls, so the current rises and the LED gets brighter.
the battery, switch, thermistor, fixed resistor and LED are drawn in one series loop
correct symbols are used: battery (two or more cells), switch, thermistor (resistor box with a bent diagonal line), fixed resistor (rectangle) and LED (diode symbol with two arrows pointing away)
the LED is drawn the right way round, so that conventional current from the positive terminal flows through it in its forward direction
the switch allows the circuit to be turned on and off
the fixed resistor limits the current, so the LED is not damaged when the thermistor's resistance is low
as the temperature of the thermistor increases, its resistance decreases
so the total resistance of the circuit decreases and the current increases (for the same battery potential difference)
the larger current makes the LED brighter, warning that the motor is getting hot
Marked with levels of response: the full level descriptors are in the app.