4.3.2a Series circuits

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Question 13

A student investigates a circuit containing different combinations of resistors to determine the resistance $R$ of resistor $X$ .

In Circuit A, resistor $X$ is connected in series with a single $Ω5.0\,\Omega$ resistor, an ammeter, and a power supply. A voltmeter is connected in parallel with resistor $X$ .

For Circuit B, a second $Ω5.0\,\Omega$ resistor is connected in series with the first resistor between terminals P and Q.

For Circuit C, a third $Ω5.0\,\Omega$ resistor is connected in series with the other two resistors between terminals P and Q.

The student obtains the following results:

Circuit	Potential difference $V$ / $V\text{V}$	Current $I$ / $A\text{A}$
A	$3.8$	$0.37$
B	$2.9$	$0.28$
C	$2.3$	$0.22$

Calculate the value of the resistance $R$ of resistor $X$ for each circuit (A, B, and C) using the equation:

\frac{V}{I}

Give your answers to 3 significant figures.

[3]

A student suggests that the value of $R$ should be constant. State whether your results from part (a) support this suggestion. Justify your statement by comparing the calculated values of $R$ (assume a limit of experimental accuracy of $10%10\%$ ).

[3]

The student wants to check the results by using one other possible arrangement of the three $Ω5.0\,\Omega$ resistors between terminals P and Q.

Describe one other arrangement of three $Ω5.0\,\Omega$ resistors between P and Q.
Calculate the total resistance of this new arrangement.

[2]

The student decides to replace the resistor combinations between P and Q with a single variable resistor to vary the current in the circuit.

Describe the circuit symbol for a variable resistor.
State one advantage of using a variable resistor to vary the current rather than using different series combinations of fixed resistors.

[2]

4.3.2a Series circuits

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Question 13

A student investigates a circuit containing different combinations of resistors to determine the resistance $R$ of resistor $X$ .

In Circuit A, resistor $X$ is connected in series with a single $Ω5.0\,\Omega$ resistor, an ammeter, and a power supply. A voltmeter is connected in parallel with resistor $X$ .

For Circuit B, a second $Ω5.0\,\Omega$ resistor is connected in series with the first resistor between terminals P and Q.

For Circuit C, a third $Ω5.0\,\Omega$ resistor is connected in series with the other two resistors between terminals P and Q.

The student obtains the following results:

Circuit	Potential difference $V$ / $V\text{V}$	Current $I$ / $A\text{A}$
A	$3.8$	$0.37$
B	$2.9$	$0.28$
C	$2.3$	$0.22$

Calculate the value of the resistance $R$ of resistor $X$ for each circuit (A, B, and C) using the equation:

\frac{V}{I}

Give your answers to 3 significant figures.

[3]

The student wants to check the results by using one other possible arrangement of the three $Ω5.0\,\Omega$ resistors between terminals P and Q.

Describe one other arrangement of three $Ω5.0\,\Omega$ resistors between P and Q.
Calculate the total resistance of this new arrangement.

[2]

The student decides to replace the resistor combinations between P and Q with a single variable resistor to vary the current in the circuit.

Describe the circuit symbol for a variable resistor.
State one advantage of using a variable resistor to vary the current rather than using different series combinations of fixed resistors.

[2]

4.3.2a Series circuits

Question 13

Markscheme

4.3.2a Series circuits

Question 13

Markscheme

4.3.2a Series circuits

Question 13

4.3.2a Series circuits Questions

4.3.2a Series circuits

Question 13

4.3.2a Series circuits Questions