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

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.
        
     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.
   
2. Hang the unloaded spring and record the pointer readings
   x_o………………………………………………………….…………………………. 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.
   
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
  
• 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/_n 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)
        
     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
     • x_o = 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.