Standard circuit diagram symbols

A student used an electromagnet to investigate magnetism.

Figure 12 shows the apparatus.

This is the method used.

1. Turn on the power supply.

2. Record the current on the ammeter.

3. Count the number of paperclips picked up by the electromagnet.

4. Turn off the power supply to release the paperclips.

5. Adjust the power supply and repeat steps 1 to 4 for different values of current.

Draw the circuit symbol for an ammeter in the space below.

Table 1 shows the results.

Complete Figure 13.

You should:

plot the data from Table 1

draw a line of best fit.

The first point has been plotted for you.

The student repeated the investigation using an electromagnet with half as many turns of wire.

How does using fewer turns of wire affect the number of paperclips picked up, for the same value of current?

Tick () one box.

Fewer paperclips will be picked up.

The same number of paperclips will be picked up.

More paperclips will be picked up.

Electromagnets are used in recycling centres to move magnetic materials.

Which two of the following materials are magnetic?

Tick () two boxes.

Cobalt

Copper

Lead

Magnesium

Nickel

Why is an electromagnet more useful than a permanent magnet in a recycling centre?

A thermistor is an electrical component.

What is the circuit symbol for a thermistor?

Tick (✓) one box.

A student investigated how the resistance of a thermistor varies with temperature.

Figure 15 shows the results.

Suggest why the student was not able to take measurements at temperatures below 20 °C.

The student used an ammeter and a voltmeter to take measurements to determine the resistance of the thermistor.

Describe a method the student could have used to obtain the results shown in Figure 15.

Figure 15 is repeated below

Use the Physics Equations Sheet to answer Questions 10.4 and 10.5.

Write down the equation which links current (I), potential difference (V) and resistance (R).

The potential difference across the thermistor was 6.0 V.

Determine the current in the thermistor when the temperature of the thermistor was 40 °C.

Use Figure 15.

An oven is connected to the mains electricity supply using a three-core cable.

Figure 3 shows the three-core cable.

The insulation covering the earth wire has green and yellow stripes.

Give the colours of the insulation covering the live wire and the neutral wire.

A thermistor is used as part of a temperature sensor in the oven.

What is the circuit symbol for a thermistor?

Tick (✓) one box.

Figure 4 shows how the resistance of the thermistor in the oven varies with temperature.

Which statement describes the relationship shown in Figure 4 ?

Tick (✓) one box.

As temperature increases, resistance decreases.

As temperature increases, resistance stays the same.

As temperature increases, resistance increases.

Which temperature range shows the greatest decrease in the resistance of the thermistor?

Tick (✓) one box.

Between 50 and 100 °C

Between 100 and 150 °C

Between 150 and 200 °C

Between 200 and 250 °C

The resistance of the heating element in the oven is 5.0 Ω.

The current in the heating element is 12 A.

Calculate the power output of the heating element.

Use the equation:

power = (current)² × resistance

Calculate the energy transferred by the oven when 8000 C of charge flows through the heating element.

The potential difference across the heating element is 230 V.

Use the equation:

energy transferred = charge flow × potential difference

An LED on the oven is connected to an alternating current supply.

When the supply is switched on, the LED flashes on and off continuously.

Explain why.

A thermistor is used in an oven as part of a temperature sensor.

Draw the circuit symbol for a thermistor.

Figure 11 shows how the resistance of the thermistor varies with temperature.

Identify the temperature range when the thermistor is most sensitive to temperature change.

Tick (✓) one box.

Between 50 and 100 °C

Between 100 and 150 °C

Between 150 and 200 °C

Between 200 and 250 °C

The potential difference across the thermistor is 15 V.

The current in the thermistor is 0.015 A.

Calculate the energy transferred by the thermistor in 20 minutes.

The power output of the heating element in the oven is 0.72 kW.

The current in the heating element in the oven is 12 A.

Calculate the resistance of the heating element.

Figure 7 shows part of the magnetic field around a bar magnet.

Figure 7

Complete Figure 7 to show the magnetic field around the bar magnet.

You should:

• draw one more magnetic field line

• show the direction of the magnetic field.

A student made an electromagnet from a metal nail and a coil of wire.

Figure 8 shows the electromagnet held in a clamp and connected to a circuit.

When the switch was closed, the electromagnet attracted paper clips.

Which metal should be used for the nail?

Tick (✓) one box.

The student varied the number of turns of wire around the nail.

The student recorded how many paper clips the electromagnet could hold.

Table 1 shows the results.

Predict value X in Table 1.

The student increased the resistance of the variable resistor.

What is the circuit symbol for a variable resistor?

Tick (✓) one box.

Complete the sentences.

Choose answers from the box.

Each answer may be used once, more than once or not at all.

When the resistance of the variable resistor was increased, the current in

the electromagnet.

When the resistance of the variable resistor was increased, the number of paper

clips the electromagnet could hold.

Figure 9 shows an electromagnet being used at a scrapyard.

Give two advantages of using an electromagnet to sort scrap metal compared with using a permanent magnet.

A student investigated how the power output of a filament lamp varied with the current in the lamp.

Figure 15 shows part of the circuit the student used.

To calculate power output the student measured the current in the lamp and the potential difference across the lamp.

Complete Figure 15 by adding an ammeter and a voltmeter to make the measurements.

Use the correct circuit symbols.

Which energy store in the battery decreases when the lamp is switched on?

What happens to the energy transferred by the lamp?

Figure 16 shows the results.

Describe how varying the current affects the power output of the filament lamp.

Write down the equation which links current (I), power (P) and resistance (R).

Determine the resistance of the lamp when the current in the lamp is 0.22 A

A student investigated how the power output of a filament lamp varied with the current in the lamp.

Figure 1 shows part of the circuit the student used.

To calculate power output the student measured the current in the lamp and the potential difference across the lamp.

Complete Figure 1 by adding an ammeter and a voltmeter to make the measurements.

Use the correct circuit symbols.

Which energy store in the battery decreases when the lamp is switched on?

What happens to the energy transferred by the lamp?

Figure 2 shows the results.

Describe how varying the current affects the power output of the filament lamp.

Write down the equation which links current (I), power (P) and resistance (R).

Determine the resistance of the lamp when the current in the lamp is 0.22 A

Some security lights automatically switch on when it gets dark.

Figure 7 shows a security light.

Figure 8 shows part of a circuit that can be used to switch the security light on and off.

The circuit symbol for the LDR in Figure 8 is not correct.

Which is the correct circuit symbol for the LDR?

Tick (✓) one box.

The security light turns on when the potential difference across the LDR is 2.0 V

Determine the resistance of the LDR when the potential difference across the LDR is 2.0 V

Use Figure 8.

A charge of 3.24 C flows through the LDR in 40.0 minutes.

Calculate the current in the LDR.

Sometimes dirt can cover the LDR on the security light.

What effect would dirt on the LDR have on the security light?

Tick (✓) one box.

A student investigated the electrolysis of potassium chloride solution.

Figure 1 shows the apparatus used.

The student used the piece of equipment labelled A to measure the volume of gas collected.

What is the piece of equipment labelled A ?

Tick (✓) one box.

What does the circuit symbol B represent?

Complete the sentence.

Choose the answer from the box.

Direct current (dc) is supplied to the circuit.

What is direct current?

Tick (✓) one box.

Potassium chloride solution contains potassium (K⁺) ions and chloride (Cl^–) ions.

Why are chloride ions attracted to the positive electrode?

Hydrogen gas is produced at the negative electrode.

Which test should the student use to identify hydrogen gas?

Tick (✓) one box.

Hydrogen ions and potassium ions move to the negative electrode.

Hydrogen gas is produced at the negative electrode.

Why is hydrogen gas produced at the negative electrode?

Tick (✓) one box.

The student measured the volume of gas collected at each electrode every minute for 25 minutes.

Figure 2 shows the results.

Describe one similarity and one difference in the volume of hydrogen and the volume of chlorine collected during the 25 minutes.

Use Figure 2.

A student investigated how the resistance of a thermistor varies with temperature.

The student made measurements to determine the resistance of the thermistor at room temperature. He used an ammeter and a voltmeter.

Complete the circuit diagram to show a circuit the student could use.

The student repeated the measurements with the thermistor at different temperatures.

He plotted a graph of resistance against temperature.

Figure 6 shows the graph.

One set of readings was:

• potential difference = 5.60 V

• current = 0.04 A

Determine the temperature of the thermistor.

Explain how the graph shows that the thermistor is most sensitive to changes in temperature between 20 °C and 25 °C