Table shows the results of an experiment to measure the resistance of a carbon resistor whose resistance is given by the manufacturer as 47 Ω ± 10 % . Potential difference/ V Current / A 2.1 0.040 4.0 0.079 6.3 .0128 7.9 0.192 10.0 0.202 12.1 0.250 Plot a graph to show the I - V Characteristic of this resistor.

Carbon resistor with resistance R = 47 Ω ± 10 % Given by the manufacturer. I - V characteristic of the resistor according to the results of the experiment is drawn below. From Ohm's law we have V = I R . So, we get an equation of straight line passing through the origin, so the graph should pass through origin.

Table shows the results of an experiment to measure the resistance of a carbon resistor whose resistance is given by the manufacturer as 47 Ω ± 10 % . Potential difference/ V Current / A 2.1 0.040 4.0 0.079 6.3 .0128 7.9 0.192 10.0 0.202 12.1 0.250 Do the points appear to fall on a straight line that passes through the origin of the graph?

Yes, the points appear to fall on a straight line that passes through the origin of the graph except 7 . 9 . Since this point is anomalous and can be ignored.So we can say Yes all the points appear to fall on a straight line passing through origin.We all know that Ohm's law indicates that the line will pass through the origin. V = I R .

Table shows the results of an experiment to measure the resistance of a carbon resistor whose resistance is given by the manufacturer as 47 Ω ± 10 % . Potential difference/ V Current / A 2.1 0.040 4.0 0.079 6.3 .0128 7.9 0.192 10.0 0.202 12.1 0.250 Does the value of the resistance fall within the range given by the manufacturer?

Yes, the resistance fall in the range given by the resistor. The range of the manufacturer is 47 Ω ± 10 % Which implies that the range is 47 - 4 . 7 = 42 . 3 Ω to 47 + 4 . 7 = 51 . 7 Ω And since the value of resistance came out to be R = ∆ V ∆ I = 12 - 0 0 . 25 - 0 = 48 Ω ∴ The required resistance R of the resistor is 48 Ω .

The readings in this table are recorded from an experiment to measure the resistivity of silver. Diameter of the wire 0.40 ± 0.2 mm Length of wire 2.25 ± 0.5 m Resistance of wire 0.28 ± 0.01 Ω Calculate the percentage uncertainty in each of the variables.

Percent error is the difference between estimated value and the actual value in comparison to the actual value and is expressed as a percentage. The percentage error in each of the variables are: Diameter of wire = 0 . 02 0 . 4 × 100 = 5 % . Length of wire = 0 . 05 2 . 25 × 100 = 2 . 22 % . Resistance of wire = 0 . 01 0 . 28 × 100 = 0 . 44 % .

The readings in this table are recorded from an experiment to measure the resistivity of silver. Use your table to calculate the absolute uncertainty in the value of the resistivity obtained in the experiment.

The percentage error in each of the variables are: Diameter of wire = 0 . 02 0 . 4 × 100 = 5 % . Length of wire = 0 . 05 2 . 25 × 100 = 2 . 22 % . Resistance of wire = 0 . 01 0 . 28 × 100 = 0 . 44 % . Resistivity of a material is given by the formulae: ρ = R A l So, absolute change in the value of the resistivity obtained in the experiment is = ∆ R + ∆ A + ∆ l = 0 . 44 + 2 . 22 + 5 = 7 . 66

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AS and A Level

IMPORTANT

Earn 100

Graph of resistance $R$ against voltage $V$ for a wire of pure iron kept at a constant temperature:

Graph of resistance $R$ against voltage $V$ for a wire of impure iron kept at a constant temperature:

Explain how the graphs would change if the wires were kept at a higher, but still constant, temperature.

Important Questions on Resistance and Resistivity

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>BEFORE YOU START>Q ●

What are units of current, charge, potential difference, e.m.f., resistance?

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>Question>Q 1

Table shows the results of an experiment to measure the resistance of a carbon resistor whose resistance is given by the manufacturer as $47 Ω \pm 10 %$ .

Potential difference/ V	Current / A
2.1	0.040
4.0	0.079
6.3	.0128
7.9	0.192
10.0	0.202
12.1	0.250

Plot a graph to show the $I - V$ Characteristic of this resistor.

EASY

AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>Question>Q 1

Table shows the results of an experiment to measure the resistance of a carbon resistor whose resistance is given by the manufacturer as

$47 Ω \pm 10 %$ .

Potential difference/ V	Current / A
2.1	0.040
4.0	0.079
6.3	.0128
7.9	0.192
10.0	0.202
12.1	0.250

Do the points appear to fall on a straight line that passes through the origin of the graph?

EASY

AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>Question>Q 1

Table shows the results of an experiment to measure the resistance of a carbon resistor whose resistance is given by the manufacturer as $47 Ω \pm 10 %$ .

Potential difference/ V	Current / A
2.1	0.040
4.0	0.079
6.3	.0128
7.9	0.192
10.0	0.202
12.1	0.250

Does the value of the resistance fall within the range given by the manufacturer?

EASY

AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>EXAM-STYLE QUESTIONS>Q 11

Deduce how the resistance of a wire made of pure iron would change if both the diameter and the length were doubled.

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>EXAM-STYLE QUESTIONS>Q 12

The readings in this table are recorded from an experiment to measure the resistivity of silver.

Question Image

Calculate the resistivity of silver.

EASY

AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>EXAM-STYLE QUESTIONS>Q 12

The readings in this table are recorded from an experiment to measure the resistivity of silver.

Diameter of the wire	0.40 ± 0.2 mm
Length of wire	2.25 ± 0.5 m
Resistance of wire	0.28 ± 0.01 Ω

Calculate the percentage uncertainty in each of the variables.

MEDIUM

AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 10 - Resistance and Resistivity>EXAM-STYLE QUESTIONS>Q 12

The readings in this table are recorded from an experiment to measure the resistivity of silver.

Question Image

Use your table to calculate the absolute uncertainty in the value of the resistivity obtained in the experiment.

Graph of resistance R against voltage V for a wire of pure iron kept at a constant temperature: Graph of resistance R against voltage V for a wire of impure iron kept at a constant temperature: Explain how the graphs would change if the wires were kept at a higher, but still constant, temperature.

Important Questions on Resistance and Resistivity

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