Standard circuit diagram symbols

A thermistor has a resistance which changes with temperature.

Which symbol is a thermistor?

Tick (✓) one box.

A student determines the resistance of a thermistor using an ammeter and a voltmeter.

Complete the diagram to show a circuit they can use.

Diagram

The student finds the resistance of the thermistor at several different temperatures.

The graph shows their results.

Describe the trend between temperature and resistance. Include data from the graph to support your answer.

A thermistor is to be used in the range 20 °C to 40 °C.

Its resistance must change by at least 10 k over this range.

Explain why this thermistor is not suitable? Include data from the graph.

What component changes resistance when there is a change in light level ?

Some scientists are comparing the resistance of circuits.

Their first circuit contains one lamp, a cell, an ammeter, a voltmeter and some connecting leads.

Draw a circuit diagram to show how they should connect these components.

Diagram

The scientists build more circuits, each time adding one more lamp to their circuit.

The table shows their results.

Number of lamps	Potential difference across each lamp (V)	Total resistance in the circuit ()
1	6.0	5.0
2	6.0	3.8
3	6.0	3.3
4	6.0	2.9
5	6.0	2.6
6	6.0	2.4

Calculate the largest current through the cell observed by the scientists.

Use the equation: potential difference = current × resistance

Explain how the scientists connected the additional five lamps.

Use their results from the table. You can use a diagram.

Optional diagram

Draw lines to connect each circuit component with its correct symbol.

Circuit component
Symbol

The potential difference across a 3 resistor is 4.5 V.

Calculate the current in the resistor.

Use the Equation Sheet.

A teacher connects the circuit in Fig. 11.2. Fig. 11.2

Both lamps are lit. The teacher then removes lamp A from its holder but leaves the rest of the circuit unchanged.

Describe what happens. Give a reason for your answer.

The teacher connects the circuit in Fig. 11.3. Fig. 11.3

Both lamps are lit. The teacher then removes lamp A.

Describe what happens. Give a reason for your answer.

The graph shows how the current in a resistor changes when the potential difference across the resistor changes.

Which two statements about the graph are correct?

Tick (✓) two boxes.

Student A uses the electric hot plate in Fig. 11.1 to increase the temperature of water in a saucepan.

Fig. 11.1

Student A wants to calculate the thermal energy transferred to the saucepan of water.

These are the steps in their method:

1 Measure the volume of water with a balance. 2 Measure the starting temperature of the water with a thermometer. 3 Use the equation:

change in thermal energy = mass specific heat capacity change in temperature

Student A ’s method is incorrect.

Identify the two mistakes the student has made and write down the correction for each mistake.

Student A suggests wrapping insulation around the saucepan in Fig. 11.1.

Suggest another way student A can improve their experiment.

Student B uses the immersion heater in Fig. 11.2 to increase the temperature of water in a beaker.

Fig. 11.2

Describe an experiment to measure the energy transferred to the immersion heater, using the equipment in Fig. 11.2.

In your answer include:

• a method

• a circuit diagram

• an equation from the Data Sheet

• the symbol for a resistor to represent the immersion heater in your circuit.

A student does an experiment to measure the resistance of a coil of wire.

The diagrams in Fig. 15.1 show the meters used in this experiment:

Meter V measures potential difference.

Complete the table to describe meter V.

Name of meter V

Smallest change in potential difference that can be measured on meter V

Draw a circuit diagram for the experiment.

Use the symbol for a fixed resistor to represent the coil of wire that the student is testing.

Write down the values of potential difference and current shown by the meters in Fig. 15.1.

Calculate the resistance of the coil of wire.

Resistance =........

To improve the experiment, the student places the coil of wire in a beaker of water, as shown in Fig. 15.2.

Suggest two reasons why this improves the experiment.

The student adds a variable resistor in series with the wire.

Suggest two reasons why this improves the method.

A student has one cell and two lamps. She wishes to connect them so that both lamps have maximum brightness.

Draw a complete circuit diagram to show how she can achieve this.

The student then investigates an unknown component. She records values for current through the component and the potential difference across the component.

Plot a graph of the data and draw a line of best fit.

One of the points has already been completed for you.

Describe what these results show.

Calculate the resistance of the unknown component.

Use the equation: Resistance = Potential difference ÷ Current

A student wishes to draw a diagram of a circuit she has created.

Which diagram A, B, C or D shows the circuit symbol for a variable resistor?

In which circuit would a current flow?