Syllabus Edition

First teaching 2020

Last exams 2024

|

Resistivity (CIE AS Physics)

Exam Questions

2 hours38 questions
11 mark

The unit of resistivity, expressed in terms of base units, is given by                                            

             k g space x cubed space y to the power of negative 2 space end exponent z to the power of negative 3 end exponent         

Which base units are x, y and z ?

 

x

y

z

A

B

C

D

ampere

metre

metre

second

metre

ampere

second

ampere

second

second

ampere

metre

    Did this page help you?

    21 mark

    A cylindrical wire of length 10 m and diameter 2.0 mm has a resistance of 0.050 Ω.

     From which material is the wire made?

     

    Material

    Resistivity / Ω m

    A

    bronze

    1.6 × 10–7

    B

    nichrome

    1.6 ×10–6

    C

    silver

    1.6 × 10–8

    D

    zinc

    6.3 × 10–8

      Did this page help you?

      31 mark

      The resistance of one device R1 is designed to change with temperature; the resistance of another device R2 is designed to change with illumination.

       What are the names of these devices ?

       

      R1

      R2

      A

      thermistor 

      light-dependent resistor

      B

      thermistor

      potential divider

      C

      semiconductor diode 

      light-dependent resistor

      D

      semiconductor diode 

      potential divider

        Did this page help you?

        41 mark

        A light-dependent resistor (LDR) is connected in series with a resistor R and a battery.

        cie-ial-images498png

        The resistance of the LDR is equal to the resistance of R when no light falls on the LDR. When the light intensity falling on the LDR increases, which statement is correct?

        • the current in R decreases

        • the current through the LDR decreases

        • the p. d. across R decreases

        • the p .d. across the LDR decreases

        Did this page help you?

        51 mark

        A copper wire is stretched so that its diameter is reduced from 1.0 mm to a uniform 0.5 mm. The resistance of the unstretched copper wire is 0.2 Ω.

         What is the resistance of the stretched wire?

        • 0.4 Ω

        • 0.8 Ω

        • 1.6 Ω

        • 3.2 Ω

        Did this page help you?

        61 mark

        Which graph best represents the way in which the current I through a thermistor depends upon the potential difference V across it ?

        cie-ial-physics-images-9-3-e-q6

          Did this page help you?

          71 mark

          A power cable has length 2000 m. The cable is made of twelve parallel strands of copper wire, each with diameter 0.51 mm.

           What is the resistance of the cable ? (resistivity of copper = 1.7 × 10–8 Ω m)

          • 0.014 Ω

          • 3.5 Ω

          • 14 Ω

          • 166 Ω

          Did this page help you?

          81 mark

          A circuit is set up with an LDR and a fixed resistor as shown.

           cie-ial-images504png

          The voltmeter reads 4 V.

          The light intensity is increased.

           What is a possible voltmeter reading?

          • 3V

          • 4V

          • 6V

          • 8V

          Did this page help you?

          91 mark

          A cylindrical wire 4.0 m long has a resistance of 31 Ω and is made of metal of resistivity 1.0 × 10–6 Ω m.

           What is the radius of cross-section of the wire?

          • 1.0 × 10–8 m

          • 2.0 × 10–8 m

          • 6.4 × 10–8 m

          • 2.0 × 10–4 m

          Did this page help you?

          101 mark

          When a thin metal wire is stretched, it becomes longer and thinner. This causes a change in the resistance of the wire. The volume of the wire remains constant.

           Which graph could represent the variation with extension x of the resistance R of the wire ?

          cie-ial-physics-images-9-3-e-q10

            Did this page help you?

            11 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.

            cie-ial-images509png

            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

            Did this page help you?

            21 mark

            In the circuit below, the reading VT on the voltmeter changes from high to low as the temperature of the thermistor changes. The reading VL on the voltmeter changes from high to low as the level of light on the light-dependent resistor (LDR) changes.

            cie-ial-images510png

            The readings VT and VL are both high.

             What are the conditions of temperature and light level ?

             

            Temperature

            Light level

            A

            B

            C

            D

            low

            low

            high

            high

            low

            high

            low

            high

              Did this page help you?

              31 mark

              In a fire alarm system, a thermistor T has a resistance of 2000 Ω at room temperature. Its resistance decreases as the temperature increases. The alarm is triggered when the potential difference between X and Y reaches 4.5 V.

              cie-ial-images511png

              What is the resistance of the thermistor when the alarm is triggered ?

              • 90 Ω

              • 150 Ω

              • 250 Ω

              • 1300 Ω

              Did this page help you?

              41 mark

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

              Their dimensions are as shown.

              cie-ial-images512png

              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

              Did this page help you?

              51 mark

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

              cie-ial-images513png

              What does the graph show?

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

              • resistivity of X = 2 × resistivity of Y

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

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

              Did this page help you?

              61 mark

              A light-dependent resistor R has a resistance of about 1 MΩ in the dark and about 1 kΩ when illuminated. It is connected in series with a 5 kΩ resistor to a 1.5 V cell of negligible internal resistance.

              cie-ial-images514png

              The light-dependent resistor is illuminated (in an otherwise dark room) by a flashing light.

               Which graph best shows the variation with time t of potential difference V across R ?

              cie-ial-physics-images-9-3-m-q6

                Did this page help you?

                71 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.

                cie-ial-images519png

                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 increases and the cross-sectional area decreases

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

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

                Did this page help you?

                81 mark

                The resistance of a thermistor depends on its temperature, and the resistance of a light-dependent resistor (LDR) depends on the illumination.

                 Under which conditions will the resistance of both a thermistor and an LDR be highest ?

                 

                Thermistor

                LDR

                A

                B

                C

                D

                highest temperature

                highest temperature

                lowest temperature

                lowest temperature

                highest illumination

                lowest illumination

                highest illumination

                lowest illumination

                  Did this page help you?

                  91 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.

                  cie-ial-images520png

                  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.

                  cie-ial-images521png

                  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

                  Did this page help you?

                  101 mark

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

                   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

                  Did this page help you?

                  11 mark

                  A thermistor and another component are connected to a constant voltage supply. A voltmeter is connected across one of the components. The temperature of the thermistor is then reduced, but no other changes are made.

                   In which circuit will the voltmeter reading increase ?

                  cie-ial-physics-images-9-3-h-q1

                    Did this page help you?

                    21 mark

                    A copper wire is to be replaced by an aluminum alloy wire of the same length and resistance.

                     Copper has half the resistivity of the alloy.

                     What is the ratio  fraction numerator d i a m e t e r space o f space a l l o y space w i r e over denominator d i a m e t e r space o f space c o p p e r space w i r e end fraction  ?

                    • square root of 2

                    • 2

                    • square root of 2

                    • 4

                    Did this page help you?

                    31 mark

                    The current in a block of semiconductor is 30.0 mA when there is a potential difference (p.d.) of 10.0 V across it. The dimensions of the block and the direction of the current in it are as shown.

                    cie-ial-images526png

                    The electrical meters used are accurate to ± 0.1 mA and ± 0.1 V. The dimensions of the block are accurate to ± 0.2 mm.

                     What is the resistivity of the semiconductor?

                    • 10.0 ± 0.2 Ω m

                    • 10.0 ± 0.3 Ω m

                    • 10.0 ± 0.5 Ω m

                    • 10.0 ± 0.8 Ω m

                    Did this page help you?

                    41 mark

                    The resistance of a metal cube is measured by placing it between two parallel plates, as shown.


                    cie-ial-images527png

                    The cube has volume V and is made of a material with resistivity ρ. The connections to the cube have negligible resistance.

                    Which expression gives the electrical resistance of the metal cube between X and Y? 

                    • rho V to the power of 1 third end exponent

                    • rho V to the power of 2 over 3 end exponent

                    • rho over V to the power of 1 third end exponent

                    • rho over V to the power of 2 over 3 end exponent

                    Did this page help you?

                    51 mark

                    A wire PQ is made of three different materials, with resistivities ρ, 2ρ and 3ρ. There is a current I in this composite wire, as shown.

                    cie-ial-images528png

                    Which graph best shows how the potential V along the wire varies with distance x from P ?

                    cie-ial-images529png

                      Did this page help you?

                      61 mark

                      A strain gauge consists of a length of wire with a uniform cross-sectional area. Its resistance is 2.50 kΩ. It is attached to a large pipe.

                       When the pipe expands, the strain gauge changes in dimensions, such that the length increases by 4% and the diameter reduced by 1%.

                       What is the new resistance of the strain gauge?

                      • 2.60 kΩ

                      • 2.65 kΩ

                      • 2.80 kΩ

                      • 3.00 kΩ

                      Did this page help you?

                      71 mark

                      The variation with temperature of the resistance RT of a thermistor is shown on the graph.

                      cie-ial-images530png

                      The thermistor is connected into the circuit shown below.

                      The battery has an e. m .f. of 9.0 V and negligible internal resistance. The voltmeter has infinite resistance.

                      cie-ial-images531png

                       What is the temperature of the thermistor when the reading on the voltmeter is 4.0 V?

                      • 2.5 °C

                      • 13.0 °C

                      • 16.0 °C

                      • 24.0 °C

                      Did this page help you?

                      81 mark

                      A conducting liquid fills a cylinder metal case to a depth y as shown in the diagram.

                      cie-ial-images533png

                      The resistance between the case and the metal rod is

                      • proportional to y

                      • proportional to y2

                      • inversely proportional to y

                      • inversely proportional to y2

                      Did this page help you?

                      91 mark

                      The following strain gauge consists of a fine metal wire, so that an applied tension on the strain gauge results in changes in the length and cross-sectional area of the wire.

                      cie-ial-images535png

                      When the length of the wire is stretched by 5%, what is the percentage change in the resistance of the wire? Assume that the volume of a wire remains constant when it is stretched.

                      • + 5%

                      • – 5%

                      • + 10%

                      • – 10%

                      Did this page help you?

                      101 mark

                      Aluminum and copper rods are designed to have the same length and the same resistance.

                       The resistivity of copper is half that of aluminum, but its density is three times that of aluminum.

                       Determine the ratio of the mass of the aluminum rod to the mass of the copper rod.

                      • 1 over 6

                      • 2 over 3

                      • 3 over 2

                      • 6 over 1

                      Did this page help you?