Resistors: draw an appropriate circuit diagram using correct circuit symbols.

The idea

A circuit diagram is a standardised drawing that shows how components are connected without showing their physical appearance. Use the recognised symbols: a cell as a long and short parallel line, a switch as a break with a hinged line, a resistor as a rectangle, an ammeter as a circle containing A, a voltmeter as a circle containing V, and a lamp as a circle with a cross. Draw connecting wires as straight lines with right-angled corners, and place the ammeter in the series loop and the voltmeter in parallel across the component being tested. An appropriate diagram for measuring resistance therefore shows the cell, switch, ammeter and component in one loop, with the voltmeter connected across the component. Neat, correctly symbolised diagrams let an examiner or another student build the circuit exactly as intended.

What earns the marks

• Correct symbol for each component used, including cell, switch, resistor or lamp, ammeter and voltmeter.
• Ammeter drawn in series within the main loop so current passes through it.
• Voltmeter drawn in parallel across the component whose resistance is being measured.
• Continuous connecting wires with clear junctions where the voltmeter branch meets the main loop.
• A complete circuit from the cell through the switch and component and back to the cell, with no gaps other than the switch.

Common mistakes and how to put them right

• Drawing the voltmeter in the main series loop.

  Put it right by drawing the voltmeter on a parallel branch across the component.

• Using a circle with a cross for a cell or a rectangle for a lamp.

  Put it right by using the long and short parallel lines for a cell and a circle with a cross for a lamp.

• Leaving gaps in the connecting wires or omitting the switch.

  Put it right by drawing continuous wires and including the switch in the main loop.

Exam tips

• Draw the main series loop first, then add the voltmeter branch across the component so the parallel connection is obvious.
• Label each symbol with its name or value so the examiner can identify components even if a symbol is slightly untidy.
• Use a ruler for straight wires and right-angled corners, and keep the diagram large enough for the parallel branch to be clear.