Components in Series & Parallel Circuits Practice Questions

Calculate the potential difference across lamp L1.

potential difference = ............................................... V

The ammeter reads $0.30\,\mathrm{A}$.

State the current in lamp L2 and give a reason for your answer.

A third identical lamp is now connected in series in the same circuit.

Explain the effect this has on the reading on the ammeter.

Describe how the resistance of a light-dependent resistor (LDR) varies as the light intensity falling on it increases.

Describe how the resistance of a thermistor varies as its temperature increases.

A thermistor is connected in series with a fixed resistor, an ammeter and a cell.

The thermistor is placed in a beaker of water which is then heated.

Explain what happens to the reading on the ammeter as the water is heated.

State which graph, A, B or C, was obtained for each of the components below.

(i) a fixed resistor at constant temperature

(ii) a filament lamp

(iii) a diode

State the total resistance of the two resistors.

total resistance = ............................................... $\Omega$

Calculate the current in the circuit.

current = ............................................... A

Calculate the potential difference across the $45\,\Omega$ resistor.

potential difference = ............................................... V

The student first connects the two resistors in series to the $4.0\,\mathrm{V}$ supply.

Show that the current in the circuit is $0.25\,\mathrm{A}$.

The resistors are now connected in parallel, as shown in Figure 3.

Calculate the total current taken from the supply.

current = ............................................... A

Explain why the total resistance of the two resistors in parallel is less than the resistance of one resistor on its own.

Explain why the ammeter is connected in series with the lamp but the voltmeter is connected in parallel with it.

Describe how the student should use this circuit to find how the resistance of the lamp changes with current.

Suggest one source of error in this investigation and describe how the student could reduce its effect.

Use the table to describe how the potential difference of the battery is shared in the series circuit and in the parallel circuit.

Calculate the resistance of one lamp in the series circuit.

resistance = ............................................... $\Omega$

Show that the resistance of each lamp in the parallel circuit is greater than in the series circuit, and explain why.

Show that the current in the circuit is $0.010\,\mathrm{A}$.

Calculate the resistance of the thermistor.

resistance = ............................................... $\Omega$

The thermistor is now warmed with a hair dryer.

Explain the effect this has on the reading on the voltmeter.

Explain why the fixed resistor must be included in the circuit.

Calculate the resistance of the diode when the potential difference across it is $0.70\,\mathrm{V}$.

resistance = ............................................... $\Omega$

The student now reverses the connections to the diode and increases the potential difference across it up to $5\,\mathrm{V}$.

Describe and explain what the ammeter reads.