Standard circuit diagram symbols

Figure 2 shows circuit symbols for some electrical components.

A student connects a circuit to measure the current in a filament lamp.

The student uses:

• an ammeter

• a cell

• a filament lamp.

Draw a circuit diagram for a circuit the student could use to measure the current in a filament lamp.

You should use three of the circuit symbols from Figure 2.

Which component is the source of energy for the circuit?

Tick () one box.

There is a current of 1.5 A in the filament lamp for a time of 30 s.

Calculate the charge flow in the filament lamp.

Use the equation:

charge flow = current × time

The current in the filament lamp is 1.5 A when the potential difference across the filament lamp is 12 V.

Calculate the resistance of the filament lamp.

Use the equation:

Choose the unit from the box.

Figure 3 shows how the current varies with potential difference for the filament lamp.

Describe the relationship between potential difference and current for the filament lamp.

As the current in the filament lamp increases, the temperature of the filament lamp increases.

What happens to the resistance of the filament lamp as the temperature increases?

In most homes, filament lamps have been replaced with LED bulbs.

Table 1 shows information about a filament lamp and an LED bulb.

Explain the advantages of using LED bulbs instead of filament lamps.

You should include a calculation in your answer.

A student investigated how the current in a diode varies with the potential difference across the diode.

Figure 6 shows an incomplete diagram of the circuit used.

The student measured the potential difference across the diode.

Complete Figure 6 by adding the symbol for a voltmeter in the correct position.

Which component should the student adjust to change the potential difference across the diode?

Tick (✓) one box.

The student measured the current three times for each value of potential difference.

Complete the sentence.

Choose the answer from the box.

When the potential difference was 1.50 V the current measurements varied between

Figure 7 shows some of the results.

Table 2 shows the results when the potential difference was greater than 1.00 V.

Complete Figure 7.

You should:

• plot the results from Table 2

• draw a line of best fit.

Complete the sentence.

Choose the answer from the box.

Figure 7 shows that the relationship between potential difference and current for the

diode is.

The student adjusted the circuit so that the current in the diode was 1.00 A.

The student then reversed the connections to the diode.

What happened to the current in the diode when the connections were reversed?

Tick (✓) one box.

A student investigated how the current in a red LED varies with the potential difference across the LED.

Figure 3 shows an incomplete diagram of the circuit used.

Complete Figure 3 to show how the student should have connected a voltmeter and an ammeter into the circuit.

Use the correct circuit symbols.

The potential difference across the battery was +2.6 V.

The student varied the potential difference across the LED between –2.6 V and +2.6 V.

Describe how the student should have adjusted the circuit to vary the potential difference across this range.

Table 1 shows the results when the potential difference across the LED had positive values.

Figure 4 shows a graph of current against potential difference.

Complete Figure 4.

You should:

• plot the remaining points from Table 1

• draw a line of best fit.

Explain what happens to the current in the LED when the potential difference across the LED is negative.

A second student did the investigation using a blue LED.

The results for both the red LED and the blue LED showed the same pattern.

What conclusion can be made about the investigation?

Tick () one box.

The relationship between current and potential difference for an LED is non-linear.

Which of the following always shows a linear relationship between current and potential difference?

Tick () one box.

Body analysis scales use the electrical resistance of a person’s legs to estimate the percentage of water in the person’s body.

Figure 8 shows body analysis scales.

The person’s legs contain both solid tissue and water.

A student used resistors to model the solid tissue and water.

The student connected a 20 resistor in parallel with a resistor, R.

Figure 9 shows the circuit diagram.

To determine the total resistance of both resistors, a voltmeter must be connected into the circuit.

Complete Figure 9 to show where the voltmeter should be connected.

The student calculated the total resistance of the two resistors.

The student’s answer was 26 .

Explain why the student’s answer cannot be correct.

Use the Physics Equations Sheet to answer questions 06.3 and 06.4.

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

When the total resistance of the resistors was 7.5 the current in the circuit was 480 mA.

Calculate the potential difference across the two resistors.

The student investigated how the resistance of R affected the total resistance of

the circuit.

Table 2 shows the results.

Some of the results are plotted in Figure 10.

Figure 10

Complete Figure 10.

You should:

• label both axes

• plot the two remaining values from Table 2

• draw the line of best fit.

What resistance of R would give a total resistance of 4.4 ?

Use Figure 10.

The body analysis scales initially show a reading of 0.0 kg.

When the student steps onto the scales the reading is 64.8 kg.

The student steps off the scales and then immediately steps back on.

The scales now show a reading of 64.1 kg.

Complete the sentence.

The difference between the two values given by the scales is due

to a
error.

The height of the student is programmed into the scales.

The scales place the student into a category, A, B or C, based on height and mass.

Figure 11 shows how the scales use the category and the total resistance of the legs to determine the body water percentage.

The total resistance of the student’s legs is 600 k. A healthy body water percentage is between 45% and 65%.

The different measurements of the mass of the student mean that the student could be in either category A or category B.

Evaluate if the student has a healthy body water percentage.

Body analysis scales use the electrical resistance of a person’s legs to estimate the percentage of water in the person’s body. Figure 3 shows body analysis scales.

The person’s legs contain both solid tissue and water. A student used resistors to model the solid tissue and water. The student connected a 20 resistor in parallel with a resistor, R. Figure 4 shows the circuit diagram.

To determine the total resistance of both resistors, a voltmeter must be connected into the circuit. Complete Figure 4 to show where the voltmeter should be connected.

The student calculated the total resistance of the two resistors. The student’s answer was 26 . Explain why the student’s answer cannot be correct.

Use the Physics Equations Sheet to answer questions 02.3 and 02.4.

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

When the total resistance of the resistors was 7.5 the current in the circuit was 480 mA. Calculate the potential difference across the two resistors.

The student investigated how the resistance of R affected the total resistance of

the circuit. Table 1 shows the results.

Some of the results are plotted in Figure 5.

Figure 5

Complete Figure 5. You should:

• label both axes

• plot the two remaining values from Table 1

• draw the line of best fit.

What resistance of R would give a total resistance of 4.4 ? Use Figure 5.

The body analysis scales initially show a reading of 0.0 kg.

When the student steps onto the scales the reading is 64.8 kg. The student steps off the scales and then immediately steps back on. The scales now show a reading of 64.1 kg.

Complete the sentence. The difference between the two values given by the scales is due

The height of the student is programmed into the scales. The scales place the student into a category, A, B or C, based on height and mass. Figure 6 shows how the scales use the category and the total resistance of the legs to determine the body water percentage.

The total resistance of the student’s legs is 600 k. A healthy body water percentage is between 45% and 65%. The different measurements of the mass of the student mean that the student could be in either category A or category B. Evaluate if the student has a healthy body water percentage.

A student investigated how the potential difference across a filament lamp affects the current in the lamp.

Figure 1 shows the circuit the student used.

Figure 2 shows a circuit symbol.

What component does the symbol represent?

Tick (✓) one box.

Which component from Figure 1 did the student use to adjust the potential difference across the lamp?

When the voltmeter was not connected to the circuit it gave a reading of 0.4 volts.

How can the student correct all the readings taken from the voltmeter?

Tick (✓) one box.

The student recorded three values of current for each potential difference.

Table 1 shows the results for 2.5 volts.

Calculate the mean current in the lamp.

Calculate the power of the lamp when the potential difference across the lamp was 4.8 V

The current in the lamp was 0.75 A

Use the equation:

power = potential difference × current

Calculate the resistance of the lamp when the potential difference across the lamp was 4.8 V

The current in the lamp was 0.75 A

Use the equation:

Complete the sentence.

Choose answers from the box.

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

Increasing the current in a filament lamp makes the temperature

Which graph shows the relationship between potential difference and current for a filament lamp?

Tick (✓) one box.

A filament lamp breaks if the electric current in the filament becomes too big.

What is the correct symbol for a filament lamp?

Tick (✓) one box.

What is meant by an electric current?

Tick (✓) one box.

A manufacturer investigated the maximum current value of some filament lamps.

Figure 6 shows the symbols for an ammeter, a battery and a variable resistor.

The manufacturer connected an ammeter, battery, filament lamp and variable resistor in series.

Draw a circuit diagram to show the manufacturer’s circuit.

Include the symbol for a filament lamp from Question 03.1

How could the manufacturer increase the current in the filament lamp?

Tick (✓) one box.

When the potential difference across a filament lamp was 0.75 V, the current in the filament lamp was 0.16 A.

Calculate the power of the filament lamp.

Use the equation:

power = potential difference × current

Write down the equation which links charge flow (Q), current (I) and time (t).

The manufacturer increased the current in the filament lamp to 200 mA.

Calculate the charge flow through the filament lamp in 15 s.

The manufacturer increased the current in the filament lamp from 200 mA.

The filament in the lamp broke when the current reached 320 mA.

How many times greater than 200 mA was the current at which the filament broke?

The manufacturer tested lots of filament lamps.

The current at which the filament lamps broke was 320 ± 60 mA.

What is the range of currents at which the filament lamps broke?

Tick (✓) one box.

Figure 9 shows a mobile phone with its battery removed.

A student measured the potential difference across the battery and then put the battery into the phone.

What is the equation linking current (I), potential difference (V) and resistance (R)?

Tick (✓) one box.

The current in the electronic circuit in the mobile phone was 0.12 A.

The potential difference across the battery was 3.9 V.

Calculate the resistance of the electronic circuit in the mobile phone.

Write down the equation which links energy (E), power (P) and time (t).

The battery was fully charged when it was put into the mobile phone.

The battery discharged when the mobile phone was switched on.

The average power output of the battery as it discharged was 0.46 watts.

The time taken to fully discharge the battery was 2500 minutes.

Calculate the energy transferred by the battery.

The mobile phone includes a sensor to monitor the temperature of the battery.

Figure 10 shows the circuit symbol for a component used in the sensor.

What component does the circuit symbol shown in Figure 10 represent?

The temperature of the component in Figure 10 increases.

The potential difference across the component remains constant.

Explain what happens to the current in the component.

Figure 1 shows a mobile phone with its battery removed.

A student measured the potential difference across the battery and then put the battery into the phone.

What is the equation linking current (I), potential difference (V) and resistance (R)? Tick (✓) one box.

The current in the electronic circuit in the mobile phone was 0.12 A. The potential difference across the battery was 3.9 V. Calculate the resistance of the electronic circuit in the mobile phone.

Write down the equation which links energy (E), power (P) and time (t).

The battery was fully charged when it was put into the mobile phone. The battery discharged when the mobile phone was switched on. The average power output of the battery as it discharged was 0.46 watts. The time taken to fully discharge the battery was 2500 minutes. Calculate the energy transferred by the battery.

The mobile phone includes a sensor to monitor the temperature of the battery.

Figure 2 shows the circuit symbol for a component used in the sensor.

What component does the circuit symbol shown in Figure 2 represent?

The temperature of the component in Figure 2 increases. The potential difference across the component remains constant. Explain what happens to the current in the component.

A student investigated how the resistance of a wire varies with the length of the wire. Figure 1 shows the circuit used.

The symbols for the voltmeter and ammeter in Figure 1 are not complete. Complete the symbols for the voltmeter and ammeter in Figure 1.

Which variable is the independent variable? Tick (✓) one box.

Which variable is the dependent variable? Tick (✓) one box.

The student took repeat readings of potential difference for a 30 cm length of the wire. The readings were: 0.16 V 0.17 V 0.15 V

Calculate the mean potential difference.

The length of the wire was increased to 60 cm The current in the wire was 0.50 A The mean potential difference across the wire was 0.32 V

Calculate the resistance of the 60 cm length of wire. Use the equation:

Calculate the power dissipated in the 60 cm length of wire. Use the equation: power = potential difference × current

Calculate the charge flow when there is a current of 0.50 A in the wire for 17 s Use the equation: charge flow = current × time

Figure 2 is a sketch graph of the results.

The student repeated the investigation using a thicker wire made from the same metal. For the same length, the thicker wire has a lower resistance. Draw a line on Figure 2 to show how the resistance of the thicker wire varies

Figure 5 shows the inside of a plug.

The plug is not wired correctly. What should be done to connect the wires in the plug correctly?

The correctly wired plug and cable connects a washing machine to the mains electricity supply.

Give the potential difference and frequency of the mains electricity supply in the UK.

The washing machine is switched on. What is the potential difference between the neutral wire and the earth wire?

The plug has a fuse. Draw the circuit symbol for a fuse in the space below.

The washing machine has a metal case. A fault causes the live wire to make an electrical connection with the metal case of the washing machine.

The earth wire is not connected to the metal case of the washing machine. Explain why it would not be safe for a person to touch the metal case.

The earth wire is now connected to the metal case of the washing machine. Explain why it would now be safe for a person to touch the metal case, even if the live wire touches the metal case.

Figure 1 shows the inside of a plug.

The plug is not wired correctly. What should be done to connect the wires in the plug correctly?

The correctly wired plug and cable connects a washing machine to the mains electricity supply.

Give the potential difference and frequency of the mains electricity supply in the UK.

The washing machine is switched on. What is the potential difference between the neutral wire and the earth wire?

The plug has a fuse. Draw the circuit symbol for a fuse in the space below.

The washing machine has a metal case. A fault causes the live wire to make an electrical connection with the metal case of the washing machine.

The earth wire is not connected to the metal case of the washing machine. Explain why it would not be safe for a person to touch the metal case.

The earth wire is now connected to the metal case of the washing machine. Explain why it would now be safe for a person to touch the metal case, even if the live wire touches the metal case.

A designer made some shoes that have lights in them.

Each shoe has a switch which closes when a person puts their foot on the floor.

Figure 1 shows the circuit.

What is component X ?

Tick (✓) one box.

Complete the sentence.

Choose the answer from the box.

When the switch was closed, the current in component X was

the current in the resistor.

The designer tested how the number of cells affected the number of steps that could be taken before the lights stopped working.

Figure 2 shows the results.

Determine how many more steps could be taken when the number of cells was increased from 3 to 5

How could the designer check the repeatability of the results?

Tick (✓) one box.

When the potential difference across the resistor was 0.80 V, the current in the resistor was 0.020 A

Calculate the power dissipated by the resistor.

Use the equation: power = potential difference × current

Which other equation can be used to calculate the power dissipated by a resistor?

Tick (✓) one box.

What happens to the temperature of the resistor when there is a current in it?

There was a current of 0.020 A in the resistor for 180 seconds.

Calculate the charge flow through the resistor.

Use the equation:

charge flow = current × time

A student investigated how the current in a resistor varies with the potential difference across the resistor.

Figure 8 shows part of the circuit used.

The student connected an ammeter and a voltmeter into the circuit.

What is the correct way to connect the ammeter and the voltmeter into the circuit?

The student increased the resistance of the variable resistor.

How did increasing the resistance affect the current in the circuit?

How should the student change the circuit to give negative values for current and potential difference?

Name the type of relationship between current and potential difference for a resistor at constant temperature.

Write the equation which links current, potential difference and resistance.

The current in the resistor was 0.12 A when the potential difference across the resistor was 3.0 V

Calculate the resistance of the resistor.

A student investigated how the current in a resistor varies with the potential difference across the resistor. Figure 1 shows part of the circuit used.

The student connected an ammeter and a voltmeter into the circuit. What is the correct way to connect the ammeter and the voltmeter into the circuit?

The student increased the resistance of the variable resistor. How did increasing the resistance affect the current in the circuit?

How should the student change the circuit to give negative values for current and potential difference?

Name the type of relationship between current and potential difference for a resistor at constant temperature.

Write the equation which links current, potential difference and resistance.

The current in the resistor was 0.12 A when the potential difference across the resistor was 3.0 V Calculate the resistance of the resistor.

Figure 2 shows a circuit that a student built.

The lamp has a resistance of 10 Ω Each resistor has a resistance of 10 Ω What is the total resistance of the circuit?

Tick (✓) one box.

Explain your answer to Question 04.1

The student replaced one of the resistors with a thermistor.

Draw the circuit symbol for a thermistor in the box below.

The student increased the temperature of the thermistor. Explain how the current in the thermistor changed.

Figure 3 shows another circuit the student built.

Explain how the potential difference across the resistor and the lamp will change when the switch is closed.

Some ceiling lights in the home are connected to the mains by a two-core cable.

Figure 6 shows a ceiling light.

Suggest why some ceiling lights do not have an earth wire.

Write down the equation that links charge flow, current and time.

There is a current of 2.95 A in one of the copper wires for 60 seconds.

Calculate the charge flow through the wire.

Use your equation from question 04.2

Figure 7 shows a current potential difference graph for a piece of copper wire.

Draw another line on Figure 7 for a wire with a different resistance.

Some fuses have a thin piece of copper that melts if the current is too large.

Draw the circuit symbol for a fuse.

Describe how the movement of the copper particles in the wire changes when copper melts.

Old copper wires are melted when they are recycled.

Calculate the energy needed to melt 500 kg of copper at its melting point.

Specific latent heat of fusion of copper = 200 kJ/kg

Use the Physics Equations Sheet.