Physics Paper 2 Questions and Answers - BSJE Mock Exams 2023

• This paper consists of two sections; A and B
• Answer all the questions in section A and B in the spaces provided
• All workings must be clearly shown in the spaces provided below each question
• Non programmable silent electronic calculators may be used.

                                                                                          SECTION A (25marks)

                                                        Answer all the questions in this section in the spaces provided

1. Figure 1 below shows the set – up for a simple cell.
                                                          
   1. Explain how electrode A becomes negative                     (1mk)
   2. Explain why the bulb goes off after only a short time. (1mk)
2.  
   1. Figure 2 shows an object, a screen and light sources X, Y and Z.
                                                
      1. Complete the diagram to show the formation of a shadow   (2mks)
      2. State one property of the object that makes it possible for its shadow to be formed  (1mk)
3. A highly negatively charged rod is gradually brought close to the cap of a positively charged electroscope. It is observed that the leaf collapses initially and then diverges. Explain the observation. (2mks)
4. Distinguish between thermionic emission and photoelectric effect. (1mk)
5. Explain why mains electricity is transmitted through alternating current and not direct Current (1mk)
6. Figure 3 shows two mirrors inclined at an angle of 30° to each other. A ray of light is incident on mirrorM₁ as shown
                                                                              
   Sketch the path of the ray to show its reflection (1mk)
7. Figure 4 below shows sound waves in air produced by a vibrating tuning fork.  R is an air molecule on the path of the waves.
                                                    
   1. Using a line, indicate on the diagram a distance d equal to one wavelength of the wave. (1mk)
   2. In the space provided below, show with an arrow the direction of motion of the air molecule R as the waves pass. (1mk)
8. Figure 5 below shows a bar magnet attracting steel pin as shown
                                                                         
   State and explain what would happen when a North pole of a bar magnet is brought near the tips of steel pin X and Y. (2mks)
9. Figure 6 below shows a wave profile for a wave whose frequency is 5Hz.
                                
   Determine the value of t8. (2mks)
10. Figure 7 below shows circular waves originating from the principal focus F of a concave mirror and moving towards the mirror.
                                                                                
    Complete the diagram to show the reflected waves. (1mk)
11. Two heating coils A and B connected in parallel in a circuit produces power of 36W and 54W respectively. What is the ratio of the resistance of B to that of A (3mks)
12. Figure 8 below shows the path of light through a transparent material placed in air.
                                         
    Calculate the refractive index of the transparent material. (3mks)
13. Figure 9 below shows an image; I formed by an object placed in front of a convex mirror. On the diagram draw appropriate rays and locate the position of the object. (2mks)
                               
                                                                                   SECTION B (55 marks)
                                                  Answer all the questions in this section in the spaces provided
14.  
    1. Figure 10 below shows two charged plates close to each other
                                                         
       1. Complete the diagram to show the electric field patterns between the plates  (1 mark)
       2. Without changing the area of overlap, suggest any one way of increasing the charge stored per unit voltage on the plates          (2 mks)
    2. Figure 11 shows two coils P and Q placed close to each other. When the switch S is closed, an e.m.f is induced in coil Q. Similarly, an e.m.f is induced in coil Q when the switch S is opened.
                                           
       Explain why the induced current in coil Q is higher when the switch S in coil P is opened than when it is closed. (2 mks)
    3. The diagram in Figure 12 below shows an induction coil used to produce sparks.
       
       1. Name parts labeled A, and C (2mks)
          A……………
          C……………
       2. Briefly explain how the induction coil works. (3mks)
    4. State the function of part B in the diagram. (1mk)
15.  
    1. Figure 13 below shows a graph of resistance against reciprocal of current. Use it to answer the questions that follow.
       
       1. Find the internal resistance, r. (2mks)
       2. Determine the e.m.f, E of the cell. (2mks)
    2. Three resistors of resistance 2 Ω, 3 Ω and 4 Ω, are to be connected to a cell such that they have the least effective resistance.
       1. Draw a circuit to show how they can be connected to achieve this. (1mk)
       2. Determine the least effective resistance of the three resistors. (2mks)
    3. An electric iron rated 240V, 750w is to be connected to a 240v mains supply through a 3A fuse.  Determine whether the fuse is suitable or not. (3mks)
16.  
    1.  
       1. Name the metal used to shield X-rays operators from the radiation. Give reasons why it is used. (2mks)
       2. In a television set, magnetic fields are preferred for use as deflection system instead of electric fields. Explain. (2mks)
    2. Figure 14 below show regions of the complete electromagnetic spectrum.  
       
       1. Name the colour of light at X and Y (2mks)
          X ………………
          Y ………………
       2. Name a suitable detector for radiation B (1mk)
    3. A student connected a circuit as shown in Figure 15 below, hoping to produce a rectified output.
                             
       1. Sketch the graph of the output on the CRO screen in the space below.  (1mk)
       2. Explain how this output is produced (2mks)
    4. The figure shows a current – carrying conductor in a magnetic field direction of force on the wire is as shown by the arrow.
                                       
       State the polarities of A and B. (2mks)
       X  ……………………
       Y. ……………………
17.  
    1. A typical nuclear fission reaction in a nuclear reactor is given below.
                       
       1. What is meant by nuclear fusion? (1mk)
       2. Find the value of x. (1mk)
       3. How are the neutrons produced used in the reactor? (1mk)
    2. Figure 16 below shows the diagram of a Geiger – Muller tube connected to a power supply and a pulse counter.
                                        
       1. Why should the Argon gas be at low pressure? (1mk)
       2. State the purpose of the bromine gas in the tube          (1mk)
       3. Suggest one way of increasing the sensitivity of the tube  (1mk)
    3. Figure 17 below shows an arrangement used to investigate photoelectric effect
                                             
       1. What is the purpose of the colour filter? (1mk)
       2. State two measurable quantities in this set up (2mks)
       3. State how the intensity of light affects photo current (1mk)
18.  
    1. Under what conditions does a converging lens form Virtual images (1 mk)   
    2. Sketch on a diagram to illustrate how a convex lens is used as a magnifying glass. (3mks)
    3. The diagram in Figure 18 below shows a three-pin plug.
                                                                    
       1. Name the colour of conductors P and Q (2 marks)
          P ……………………
          Q ……………………
       2. Why is the earth pin longer than the rest in the three-pin plug shown above? (1 mark)
    4. Figure 19 shows the displacement of a practice in progressive wave incident on a boundary between deep and shallow regions.
                                   
       1. Complete the diagram to show what is observed after boundary. (1mk)
       2. Explain the observation in (i) above.    (1mk)
    5. Concave mirrors are used by dentists to examine teeth. By use of a ray diagram show how this is achieved. (3 marks)

                                                                            MARKING SCHEME

                                                                                        SECTION A (25 MARKS)

1.  
   1. Zinc ions (Zn²⁺) dissolve in dilute H₂SO₄/acid leaving electrons on the electrode.
   2. n – Due to polarization                                                                                   
         − Due to insulation of the copper electrode by hydrogen gas bubble.      (Any)
2.  
   1.  
      1.  
           
      2.  it is opaque/ it blocks light rays from reaching the screen.
3.  
   • Electrons are repelled from the cap to the leaf and plate neutralizing the positive charges making the leaf fall.
   • As more electrons are repelled the leaf and plate acquire net negative charge hence repell.
4. Thermionic emission is the process by which electrons are emitted from a metal surface while photoelectric effect is the process by which electrons are emitted from a metal surface when radiation of sufficient energy is shone on it
5. a.c can be stepped up and down while d.c cannot be stepped up or down. 
6.  
                               
7.  
                      
8.  
   • The tips of the pins are attracted to the N-pole of the bar magnet
   • The tips of the pins have induced S-pole hence attracted to the N-pole.
9.  
    T = ¹/_f = ¹/_s = 0.02s
    t₈ = 2T = 2 X 0.2 = 0.4s
10. // 
                     
11.  
                             
12.    
       C = 139°– 90° = 49°
        n  =      1     =    1        =  1.325
                  sin c     sin 49°
13.  
                                
    
                                                                                           SECTION B
14.  
    1.  
       1. 
                                               
       2.  
          • Reducing the distance of separation between the plates
          • Inserting a better dielectric between the plates
    2.  
       • Current takes a shorter time to reduce from maximum to zero
       • Hence a more rapid change in magnetic flux.
    3.  
       1.  
          • A – Primary coil
          • C – Secondary coil
       2.  
          • When the switch is closed, soft iron core gets magnetized and attracts the armature breaking the contact and circuit.
          • The soft iron core gets magnetized and armature springs back closing the contact and current flows again.
          • The process is repeated continuously and the magnetic flux change in the core induces a large emf in the secondary circuit which causes a spark to jump across the spark gap.
    4. The capacitor prevents sparking between the contacts as they open.
15.  
    1.  
       1. - r  =  R-intercept  =  -0.4
            r  = 0.4Ω
          
          
       2. E = Gradient 
          =     4.5 − 0  = 4.5 = 5Ω
                 1 − 0.1     0.9
    2.  
       1.  
                                                  
       2.  
           1R   =   ¹/_R1    +   ¹/_R2     +    ¹/_R3
                  =  ¹/₂    +   ¹/₃    +    ¹/₄   =   ¹³/₁₂           (Any)
            ⸫       R   =   1213    =  0.9231Ω
          
          
    3.   P     =   VI
          I     =   ⁷⁵⁰/₂₄₀     =   3.125A
                ⸫ The fuse is not suitable as its rating is below the operating current
16.  
    1.  
       1.  
          • Lead
          • It has high density hence absorbs the X-Rays
       2. Magnetic fields give a wider deflection of the electron beam than electric field, hence enables a wider screen
    2.  
       1.  
          • X  − Violet
          • Y  − Red
       2. Microwaves Receiver / Diodes           Any 1
    3.  
       1.  
                
       2.  
          • When X is positive w.r.t. Y D1 is forward biased , D2 is reverse biased and current flows from X , D1, R and back.
          • When Y is positive w,r,t, X D2 is forward biased D1 is reverse biased and current flows from Y, R, D2,and back
          • The process is repeated continuously
    4.  
       • X   -    North .Pole
       • Y   -    South .Pole
17.  
    1.  
       1. The process by which two or more light atomic nuclei combine to form a single heavier one while releasing amount of energy.
       2. 235  + 1  =  148  +  85  +  X
          236  =  233  +  X
          X  = 3
       3. The neutrons hit other uranium atoms producing more neutrons and energy and the process continues.
    2.  
       1. For easier ionization / for faster ionization.
       2.  
          • Stops secondary ionization
          • absorbs secondary ions                    
          • Quenching the tube            Any 1
       3. Making the mica window thinner
    3.  
       1.  
          • To allow only one colour of light to reach the photocell
          • To absorb the unwanted colours of light                                     Any 1
       2.  
          • Stopping Potential                        
          • Frequency of the light
          • Photo Current                     Any two
       3. Increase in intensity of light increases the photo current.
18.  
    1. When the object is placed between the focal point and the lens.
    2.  
                                                 
    3.  
       1. P   -   Blue/Black
          Q   -   Red/Brown
       2.  
          • To open the blinds                                                                    Any 1
          • To earth the appliance before current starts flowing
    4.  
       1. 
                                      
       2. The velocity /speed of the wave reduces leading to decrease in wavelength of the wave
    5.