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Resistance & Resistivity (AQA A Level Physics): Exam Questions

Exam code: 7408

3 hours44 questions

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Resistance & Resistivity

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11 mark

Which of the following is a correct unit for resistivity, ρ?

  • Ω 

  • Ω m–1

  • Ω m–2

  • Ω m

Choose your answer

21 mark

Which of the following statements about resistivity is false?

  • The resistivity of a metal wire depends on temperature

  • The resistivity of a metal wire depends on length

  • Resistivity is measured in Ω m

  • Resistivity is a measure of a wire’s resistance to electric current

Choose your answer

31 mark

A student carries out an experiment to determine the resistivity of a metal wire.

She determines resistance from measurements of potential difference and the corresponding current, and measures the length of a wire with a metre rule and the diameter of the wire.

Which of the following is the most appropriate piece of equipment to measure the diameter of a metal wire?

  • A metre rule

  • An ammeter

  • A micrometer

  • A ruler

Choose your answer

41 mark

Which of the following statements about superconductors is true?

  • Superconductors are highly conducting plastic materials 

  • The resistance of a superconductor is zero below a critical temperature

  • Superconductors have very low resistance at extremely high temperatures

  • The resistance of a superconductor is near zero below its critical temperature

Choose your answer

51 mark

 Which of the following is not a possible application of superconducting material?

  • Electrical transformers

  • MRI scanners

  • Tyres for electric vehicles

  • Maglev trains

Choose your answer

61 mark

A metal wire of length 2.5 m and cross-sectional area 7.1 × 10–9 m2 has a resistivity of 2.8 × 10–7 Ω m.

What is the resistance of the wire?

  • 9.9 Ω 

  • 99 Ω 

  • 1 Ω

  • 1000 Ω

Choose your answer

71 mark

When the temperature of nickel wire increases, its ability to conduct electricity:

  • remains the same 

  • decreases 

  • remains the same at first, then decreases 

  • increases

Choose your answer

81 mark

Which graph shows how the resistance R of an NTC thermistor varies with temperature, T?

q8_resistance-_-resistivity_aqa-as-physics-mcq

    Choose your answer

    91 mark

    Which graph shows how the resistance varies with temperature for a superconducting material around its critical temperature, begin mathsize 16px style T subscript C end style?

    q9_resistance-_-resistivity_aqa-as-physics-mcq

      Choose your answer

      101 mark

      A nichrome wire of length 4.2 m and cross-sectional area 6.0 × 10–10 m2 has a resistance of 1 kΩ.

      What is the resistivity of the nichrome wire?

      • 1.4 × 10–10 Ω m 

      • 1.4 × 10–7 Ω  

      • 1.4 × 10–10 Ω 

      • 1.4 × 10–7 Ω m  

      Choose your answer

      11 mark

      Which statement about superconductors is correct?

      • The temperature at which a material becomes a superconductor is called the critical temperature

      • When a material becomes a superconductor, its resistivity is almost zero

      • Copper is a superconductor at room temperature

      • When current passes through a superconductor, the potential difference across it becomes a maximum

      Choose your answer

      21 mark

      Which graph shows the variation of the resistance with temperature for an NTC thermistor?

      q12_resistance-_-resistivity_aqa-as-physics-mcq

        Choose your answer

        31 mark

        Two wires P and Q made of the same material are connected to the same electrical supply.

        P has twice the length of Q and one-third of the diameter of Q, as shown in the diagram .

        q13_resistance--resistivity_aqa-as-physics-mcq

        What is the ratio  fraction numerator c u r r e n t space i n space P over denominator c u r r e n t space i n space Q end fraction ?

        • 2 over 3

        • 2 over 9

        • 1 over 6

        • 1 over 18

        Choose your answer

        41 mark

        Two electrically-conducting cylinders X and Y are made from the same material.

        Their dimensions are as shown. 

        q14_resistance-_-resistivity_aqa-as-physics-mcq

        The resistance between the ends of each cylinder is measured.

        What is the ratio  fraction numerator r e s i s tan c e space o f space X over denominator r e s i s tan c e space o f space Y end fraction ?

        • 2 over 1

        • 1 over 1

        • 1 half

        • 1 fourth

        Choose your answer

        51 mark

        Tensile strain may be measured by the change in electrical resistance of a strain gauge.

        A strain gauge consists of folded fine metal wire mounted on a flexible insulating backing sheet.

        The strain gauge is firmly attached to the specimen, so that the strain in the metal wire is always identical to that in the specimen.

        q15_resistance-_-resistivity_aqa-as-physics-mcq

        When the strain in the specimen is increased, what happens to the resistance of the wire?

        • it decreases, because the length decreases and the cross-sectional area increases

        • it decreases, because the length decreases and the cross-sectional area increases

        • it increases, because the length decreases and the cross-sectional area increases

        • it increases, because the length increases and the cross-sectional area decreases

        Choose your answer

        61 mark

        A researcher has two pieces of copper of the same volume. All of the first piece is made into a cylindrical resistor P of length x.

        q16_resistance-_-resistivity_aqa-as-physics-mcq

        All of the second piece is made into uniform wires each of the same length x which he connects between two bars of negligible resistance to form a resistor Q.

        q16_2_resistance-_-resistivity_aqa-as-physics-mcq

        How do the electrical resistances of P and Q compare?

        • P has a larger resistance than Q

        • Q has a larger resistance than P

        • P and Q have equal resistance

        • Q may have a larger or smaller resistance than P, depending on the number of wires made

        Choose your answer

        71 mark

        Two wires have the same length and the same resistance. Wire X is made of a metal of resistivity 1.7 × 10–8 Ω m, and wire Y is made of a metal of resistivity 5.6 × 10–8 Ω m.

        The diameter of wire X is 0.315 mm.

        What is the diameter of wire Y? 

        • 0.17 mm

        • 0.33 mm

        • 0.57 mm

        • 1.0 mm

        Choose your answer

        81 mark

        A metal wire has a length  and a cross-sectional area A.

        The wire is connected to a cell of emf ϵ, with no internal resistance, such that a current I flows in the wire.

        Which expression gives the resistivity of the wire?

        • fraction numerator I A over denominator ϵ L end fraction

        • fraction numerator ϵ A over denominator I L end fraction

        • fraction numerator I L over denominator ϵ A end fraction

        • fraction numerator ϵ I over denominator L A end fraction

        Choose your answer

        91 mark

        Which graph shows how the resistance per unit length r of a wire varies with radius  of the wire?

        q19_resistance-_-resistivity_aqa-as-physics-mcq

          Choose your answer

          101 mark

          A student carries out an experiment to determine the resistivity of a metal wire.

          She determines resistance from measurements of potential difference and the corresponding current and measures the length of a wire with a metre rule and the diameter of the wire with a micrometer.

          Each measurement is made with an uncertainty of 2 %.

          Which quantity contributes the largest uncertainty in the calculated value of resistivity?

          • Cross-sectional area, A

          • Length, l

          • Potential difference, V

          • Current, I

          Choose your answer

          11 mark

          Two wires, P and Q, each of the same length and the same material, are connected in parallel to a battery.

          The diameter of P is half that of Q.

          What fraction of the total current passes through P?

          • 0.10

          • 0.20

          • 0.50

          • 0.25

          Choose your answer

          21 mark

          An NTC thermistor suspended in a water bath and the temperature is gradually increased.

          Which of the following graphs best represents how the current I in the thermistor varies with the potential difference V across it?

          q22_resistance-_-resistivity_aqa-as-physics-mcq

            Choose your answer

            31 mark

            A conducting liquid fills a cylindrical metal case to a depth x as shown in the diagram.

            q23_resistance-_-resistivity_aqa-as-physics-mcq

            The resistance R between the case and the metal rod is correctly described by which of the following statements?

            • R ∝ x

            • R ∝ x2

            • R ∝ begin mathsize 16px style 1 over x end style

            • R ∝ begin mathsize 16px style 1 over x squared end style

            Choose your answer

            41 mark

            A wire of uniform cross-sectional area A has a resistance R.

            The wire is stretched until its length increases by 15%.

            Assuming the new wire has the same volume as before, by how much has the resistance of the wire increased?   

            • 30%

            • 32%

            • 33%

            • 35%

            Choose your answer

            51 mark

            A strain gauge consists of a length of wire with uniform cross-sectional area A and resistance 3.00 kΩ. It is attached to large pipe, such that when the pipe expands, the strain gauge changes in dimensions.

            During one particular expansion, the length increases by 5% and the diameter reduces by 10%.

            What is the new resistance of the strain gauge? 

            • 3.89 kΩ 

            • 3.88 kΩ

            • 3.87 kΩ

            • 3.86 kΩ

            Choose your answer

            61 mark

            A composite wire is made using four uniform wires of the same material but varying diameters as shown:

            q26_resistance-_-resistivity_aqa-as-physics-mcq

            Which graph correctly shows the variation of resistance R with distance d from the point X?   

            q26_2_resistance-_-resistivity_aqa-as-physics-mcq

              Choose your answer

              71 mark

              A wire of resistivity 1.5 × 10–8 Ω m has a radius of 0.25 mm and a length that is able to be wound in circles 50 times round a plastic rod of radius 1.25 cm. 

              What is the resistance of the wire?

              • 4.15 Ω 

              • 3.50 Ω 

              • 3.14 Ω 

              • 0.3 Ω 

              Choose your answer

              81 mark

              In an experiment to investigate how the potential difference V varies with length l of a copper wire of uniform cross-sectional area A, a student measures the potential difference across the wire at equal intervals of length and plots a graph.

              What are the correct dimensions of the gradient of the graph?

              • J m–2 s–1 A–1

              • J m–1 s–1 A–1

              • J m–1 s–2 A–1

              • J m–1 s–1 A–2

              Choose your answer

              91 mark

              The graph shows the variation with length l of resistance R for two wires X and Y made from the same material.

              q29_resistance-_-resistivity_aqa-as-physics-mcq

              Which of the following statements is correctly concluded from the graph?

              • cross-sectional area of X = 2 x cross-sectional area of Y

              • resistivity of X = 2 x resistivity of Y

              • when equal lengths of X and Y are connected in series to a battery, power in X = 2 x power in Y

              • when equal lengths of X and Y are connected in parallel to a battery, current in X = 2 x current in Y

              Choose your answer

              101 mark

              In a fire alarm system, a negative temperature coefficient thermistor T has a resistance of 2 kΩ at room temperature and is connected in a circuit as shown:

              q30_resistance-_-resistivity_aqa-as-physics-mcq

              The alarm is triggered when the potential difference between X and Y reaches 4.5 V.

              From room temperature, what is the percentage reduction of resistance required for the alarm to be triggered?

              • 12.5%

              • 25%

              • 66%

              • 87.5%

              Choose your answer