4.2.4a Resistance

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Question 9

A student investigates a resistor and a filament lamp connected in series.

The student adjusts the position of a crocodile clip on a resistance wire until the potential difference $VLV_{\text{L}}$ . across the lamp is $V3.0\text{ V}$ .

The ammeter used to measure the current $I$ in the circuit has major scale markings at $0.50\text{ A}$ , with $10$ small divisions between each major marking. The pointer is at the $6th6\text{th}$ small division after $A0.20\text{ A}$ .
The voltmeter used to measure the potential difference $VRV_{\text{R}}$ _ across the resistor has major scale markings at $6.0\text{ V}$ , with $10$ small divisions between each major marking. The pointer is at the $4th4\text{th}$ small division after $V4.0\text{ V}$ .

Record the values of $I$ and $VRV_{\text{R}}$ _ for $VV_{\text{L}} = 3.0\text{ V}$ .

[2]

The table below shows the results of this experiment.

$VV_{\text{L}}\text{ / V}$	$AI\text{ / A}$	$VV_{\text{R}}\text{ / V}$
$3.0$
$2.0$	$0.20$	$3.5$
$1.0$	$0.12$	$2.1$

Calculate, and record in the table, the resistance of the lamp $RLR_{\text{L}}$ . and the resistor $RRR_{\text{R}}$ . for each value of $VLV_{\text{L}}$ . Use the equations:

R_{\text{L}} = \frac{V_{\text{L}}}{I} \quad \text{and} \quad R_{\text{R}} = \frac{V_{\text{R}}}{I}

Give all your values of $RLR_{\text{L}}$ . and $RRR_{\text{R}}$ . to a consistent number of significant figures (2 or 3 significant figures).

[3]

Describe the pattern of any change in the value of $RLR_{\text{L}}$ . as $VLV_{\text{L}}$ . decreases.

[1]

State whether your results support the suggestion that the resistance $RRR_{\text{R}}$ . of the resistor is constant. Justify your statement by reference to the calculated values.

[2]

The student wishes to determine the resistance of the lamp $RLR_{\text{L}}$ . when the potential difference across the lamp $VV_{\text{L}} = 0.0\text{ V}$ . Describe how the experiment can be extended to do this with the help of a suitable graph.

[3]

Describe how a variable resistor can be connected into the circuit instead of a resistance wire to change the potential difference across the lamp, and state where a voltmeter must be connected to measure the potential difference across the resistor.

[2]

The student adjusts the position of a crocodile clip on a resistance wire until the potential difference $VLV_{\text{L}}$ . across the lamp is $V3.0\text{ V}$ .

The ammeter used to measure the current $I$ in the circuit has major scale markings at $0.50\text{ A}$ , with $10$ small divisions between each major marking. The pointer is at the $6th6\text{th}$ small division after $A0.20\text{ A}$ .
The voltmeter used to measure the potential difference $VRV_{\text{R}}$ _ across the resistor has major scale markings at $6.0\text{ V}$ , with $10$ small divisions between each major marking. The pointer is at the $4th4\text{th}$ small division after $V4.0\text{ V}$ .

Record the values of $I$ and $VRV_{\text{R}}$ _ for $VV_{\text{L}} = 3.0\text{ V}$ .

VV_{\text{L}}\text{ / V}

AI\text{ / A}

VV_{\text{R}}\text{ / V}

ΩR_{\text{L}}\text{ / }\Omega

ΩR_{\text{R}}\text{ / }\Omega

3.0

2.0

0.20

3.5

1.0

0.12

2.1

4.2.4a Resistance

Question 9

Markscheme

4.2.4a Resistance

Question 9

Markscheme

4.2.4a Resistance

Question 9

4.2.4a Resistance Questions

4.2.4a Resistance

Question 9

4.2.4a Resistance Questions