Physics Paper 3 Questions and Answers with Confidentials - MECS Cluster Joint Mock Exams 2021/2022

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PHYSICS 
PAPER 3

PRACTICAL

INSTRUCTIONS TO CANDIDATES

  • Write your name and admission number in the spaces provided.
  •  Answer ALL questions in the spaces provided in the question paper.
  • You are supposed to spend the first 15 minutes of the allowed for this paper reading the whole paper carefully before commencing the work.
  • Marks are given for a clear record of the observations actually made, their suitability, accuracy and the use made of them.
  • Candidates are advised to record their observation as soon as they are made.
  • Non programmable silent electronic calculators may be used.
  • This paper consists of 8 printed pages.
  •  Candidates should check the questions to ascertain that all the pages are printed as indicated and that no question are missing.
  • Candidates should answer the questions in English.

QUESTION 1 (20 marks)

  1. You are provided with the following;
    • A galvanometer
    • A dry cell and a cell holder
    • A switch
    • A wire labelled Y mounted on a piece of wood.
    • Eight connecting wires each with a crocodile clip at one end.
    • A resistance wire labelled AB mounted on a millimeter scale.
    • Six 10 Ohm carbon resistors
    • A jockey or crocodile clip
    • Micrometer screw gauge (to be shared)

      Proceed as follows:
      1. Set up the circuit as shown in figure below, with X being one of the 10 ohms carbon resistors.
        PhyMEcp3q1aY
      2. Close the switch. Tap the jockey at various points on the wire AB and locate point P at which the galvanometer shows zero deflection, measure and record in table below the length, where = PB.
      3. Repeat the procedure in (b) using X as two 10Ω resistors, three resistors, four resistors, five resistors and six resistors. X is the effective resistance for the parallel combination i.e. x = 10/n where n is the number of resistors in parallel.
      4. Record your readings in table below. (6mks)
        TABLE
        Number of 10Ω
        Carbon resistor
        One Two Three Four Five Six
         X (Ω)            
        L (cm)            
         1/x (Ω-1)            
         1/L(cm-1)            
      5. Plot a graph of 1/L (y-axis) against  1/x. (5mks)
      6. Determine the slope m of the graph. (2mks)
      7. Given that 1/L = R/KX + 1/K where K = 100cm. Use the graph to determine R. (2mks)
      8. Measure the diameter d and the length of wire Y. (2mks)
        =…..……..…………………………..….m
        d = ………….…………………………….. m
      9. Determine its cross-sectional area A of the wire Y. (1mk)
        A =………………………………………… m 2
      10. Determine the resistivity of the wire Y given that its Resistance, R= 1/A(2mks)

QUESTION 2 (20 marks)

PART A

You are provided with the following;

  • Meter rule
  • Retort stand, clamp and boss
  • A spring and with a pointer
  • Three masses (a 100 g and two 50g masses)
  • Stop watch

Proceed as follows

  1. Set the apparatus as shown below.
    PhyMEcp3q2aa
  2. Hang the unloaded spring and record the pointer readings
    xo………………………………………………………….…………………………. m. (1mk)
  3.          
    1. Load a mass of 150 g and determine the extension of the spring, e1 .
      e1……………………………………………………………………………. m. (1mk)
    2. Displace the 150 g mass slightly downwards and release it to oscillate vertically. Time 20 oscillations and obtain time t1 t1 ………………………………………………….. (1mk)
    3. Find periodic time T 1
      T1 …………………………………………………. (1mk)
    4. Use the equation to find the value of P-1 . (2mks)
  4.       
    1. Load a mass of 200 g and determine the extension of the spring, e2 .
      e2……………………………………………………………………………. m. (1mk)
    2. Displace the 200 g mass slightly downwards and release it to oscillate vertically.
      Time 20 oscillations and obtain time t2 .
      t2 ………………………………………………….. (1mk)
    3. Find periodic time T1
      T1 …………………………………………………. (1mk)
    4. Use the equation to find the value of P2 . (2mks)
  5. Find the average of P (2mks)
    Pav = P² + P¹
                  2

    PART B

    Apparatus
    • Lens and a lens holder
    • A candleScreen
    • A metre rule.

      Procedure
  6. Focus a distant object and estimate the focal length, f of the lens
    f …………………………………………. mm. (1mk)
  7. Set up the apparatus as shown below.
    PhyMEcp3q2bg
  8. Set the distance s= 60 cm.
    1. Adjust the position of the lens to position p where a magnified sharp image is formed on the screen. Record position P.
      P =………………………………………. cm. (1mk)
    2. Maintaining distance s, adjust the lens to position P’ where a diminished sharp image is formed on the screen. Record position, P’.
      P’ = ……………………………………… cm. (1mk)
    3. Find distance d, between the original position and final position of lens
      d = ………………………………………... cm (1mk)
  9. Using the formula s2 - d2 = 4 Find the value of q. (2mks)
  10. What physical quantity do q represent (1mk)

CONFIDENTIAL

QUESTION 1

Each candidate will require

  • Centre zero galvanometer
  • One new size D dry cell & cell holder
  • A switch
  • Eight connecting wires each with crocodile clip at one end.
  • A piece of nichrome wire swg 28 (diameter 0.32 mm) of length 30cm.
  • Teacher to mount the piece of wire on piece of wood and label it Y see
    PhyMEcp3conf
  • A resistance (nichrome wire gauge 30) wire labeled AB 100cm long mounted on a millimeter scale
  • Six 10 Ohms carbon resistors.
  • A jockey (a crocodile clip may be used)
  • A micrometer screw gauge

QUESTION 2

Each candidate will require:

  • A spiral spring of spring constant of approximately 10.0N/m.
  • A complete stand
  • A metre rule.
  • Lens (focal length = 10cm) and a lens holder.
  • A candle
  • Screen
  • Three masses (one 100g and two 50g masses)
  • A stop watch

MARKING SCHEME

QUESTION 1 (20 marks)

  1. You are provided with the following;
    • A galvanometer
    • A dry cell and a cell holder
    • A switch
    • A wire labelled Y mounted on a piece of wood.
    • Eight connecting wires each with a crocodile clip at one end.
    • A resistance wire labelled AB mounted on a millimeter scale.
    • Six 10 Ohm carbon resistors
    • A jockey or crocodile clip
    • Micrometer screw gauge (to be shared)

      Proceed as follows:
      1. Set up the circuit as shown in figure below, with X being one of the 10 ohms carbon resistors.
      2. Close the switch. Tap the jockey at various points on the wire AB and locate point P at which the galvanometer shows zero deflection, measure and record in table below the length, where = PB.
      3. Repeat the procedure in (b) using X as two 10Ω resistors, three resistors, four resistors, five resistors and six resistors. X is the effective resistance for the parallel combination i.e. x = 10/where n is the number of resistors in parallel.
      4. Record your readings in table below. (6mks)
        Number of 10Ω
        Carbon resistor
        One Two Three Four Five Six
         X (Ω) 10 5 3.333 2.5 2 1.667
         (L cm) 66.5  53.3 48.2 43.5 40.2 37.4
        1/x (Ω-1) 0.1 0.2 0.3 0.4 0.5 0.6
         1/L(cm-1) 1.515 1.876 2.075 2.299 2.488 2.674

        Plot a graph of 1/L (y-axis) against 1/x. (5mks)
        PhyMEcp3qa1di
      5. Determine the slope m of the graph. (2mks)
        • m = (2.2 - 2.5) 10‾² cm-1
                   (0.35 - 0.10) -1
          (Correct substitution = 1mk)
          (Correct evaluation with units = 1mk)
          Wrong unit = 0mk, no unit = half mark

      6. Given that where 1/L = r/KX + 1/K where K = 100cm. Use the graph to determine R. (2mks)
        • Slope = R/K
          (Correct substitution = 1mk)
          =28
          (Correct evaluation = 1mk)

      7. Measure the diameter d and the length of wire Y. (2mks)
        • I = 30.0/100 = 0.300 m ±0.01 (Value within the range and 3dp a must = 1mk)
          d = 0.32/100= 0.0032m ± 0.00002(Value within the range and 5dp a must = 1mk)

      8. Determine its cross-sectional area A of the wire Y. (1mk)
        • (Correct substitution = mk)
          A m2 (Correct evaluation = mk)

      9. Determine the resistivity of the wire Y given that its Resistance, (2mks)
        • 7.508 x 10-7m
          (Correct substitution = 1mk)
          (Correct evaluation = mk, rule for units applies)

QUESTION 2 (20 marks)

PART A

  • You are provided with the following;
  • Meter rule
  • Retort stand, clamp and boss
  • A spring and with a pointer
  • Three masses (a 100 g and two 50g masses)
  • Stop watch

    Proceed as follows
    1. Set the apparatus as shown below.
    2. Hang the unloaded spring and record the pointer readings
      • xo = student value (3d.p a must) m (1mk)
    3.    
      1. Load a mass of 150 g and determine the extension of the spring, e 1 .
        • e1 = difference in student values = 0.148 ± 0.0 m (1mk)
          (Correct subtraction = mk, correct evaluation =mk)

      2. Displace the 150 g mass slightly downwards and release it to oscillate vertically. Time 20 oscillations and obtain time t 1 .
        • t 1 = 16.37 ±  0.5 (1mk)
          (Value within the range and 2dp a must = 1mk, no unit deny a half mark)

      3. Find periodic time T 1
        • T 1 = 16.37/20 = 0.8184s
          (Correct division = mk, correct evaluation with unit=mk)
          (1mk)

      4. Use the equation to find the value of P 1 . (2mks)
        • P = 0.148/0.01616 = 9.158 m/s2
          (Correct substitution = 1mk)
          (Correct evaluation to 4sf = 1mk)
    4.       
      1. Load a mass of 200 g and determine the extension of the spring, e 2 .
        • e2 = x2 - x0 = 0.196 ±  0.01 m. (Correct subtraction =
          mk, correct evaluation=mk). (1mk)

      2. Displace the 200 g mass slightly downwards and release it to oscillate vertically. Time 20 oscillations and obtain time t 2 .
        • t 2 = 18.62 ±  0.5s (1mk)
          (Value within the range and 2dp a must = 1mk, no unit deny a half mark)

      3. Find periodic time T 1
        • T2 = 18.62/20 = 0.9310s
          (1mk) (Value within the range and
          2dp a must = 1mk, no unit deny a half mark)

      4. Use the equation to find the value of P2 . (2mks)
        • (Correct substitution = 1mk)
          (Correct evaluation to 4sf = 1mk)

    5. Find the average of P
      • (Averaging principle = 1mk). (2mks)
        (Correct evaluation to 4sf = 1mk)


        PART B
        Apparatus
      • Lens and a lens holder.
      • A candle
      • Screen
      • A metre rule.

        Procedure

    6. Focus a distant object and estimate the focal length, f of the lens
      • f mm ± 10 mm (1mk)

    7. Set up the apparatus as shown below.
    8. Set the distance s= 60 cm.
      1. Adjust the position of the lens to position p where a magnified sharp image is formed on the screen. Record position P.
        • P = Student’s value (1d.p a must) cm. (1mk)

      2. Maintaining distance s, adjust the lens to position P’ where a diminished sharp image is formed on the screen. Record position, P’.
        • P’ = Student’s value (1d.p a must) cm. (1mk)

      3. Find distance d, between the original position and final position of lens
        • d = cm (1mk)
          (Correct subtraction = mk, correct evaluation =mk)
    9. Using the formula . Find the value of q. (2mks)
      • (Correct substitution = 1mk)
      • (Correct evaluation to 4sf = 1mk)

    10. What physical quantity do q represent (1mk)
      • Focal length of the lens used.

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