Physics Paper 2 Questions and Answers - Maranda High School Mock Exams 2023

Instructions to candidates

• This paper consist of TWO sections;A and B. Answer ALL the questions in section A and B .
• ALL working must  be clearly shown. Mathematical tables, electronic calculators and slide rules may be used.
• Take h = 6.63 × 10⁻³⁴ Js, e = 1.6 ×10⁻¹⁹C, mass of electron = 9.11 × 10⁻³¹kg

Section A (25 marks)

Attempt all questions in this section in the spaces provided

1. Figure 1 shows an object placed in front of a pin-hole camera whose length X is adjustable.
   
   One of the effects of increasing length X is formation of an enlarged image. State the other effect giving a reason for your answer.  (2 marks)
2. Figure 2 shows the printing system of an inkjet printer
   
   Identify the type of charge on the charged ink drops.   (1 mark)
3. Give two benefits of high voltage transmission of electrical power.    (2 marks)
4. Figure 3 shows an aluminum ring placed between the poles of magnets.
   
                    Figure 3
   Sketch the magnetic field pattern between the poles of the magnets.     (1 mark)
5. Figure 4 below (drawn to scale) shows the image I, formed by a convex mirror. F is the virtual
   
                                                  Figure 4
   Using ray diagrams locate the position of the object and draw the object      (2 marks)
6. An electric bulb is labeled 100W, 240V. Determine the current through the filament     (2 marks)
7. State and explain how an increase in humidity affects the speed of sound in air.    (2 marks)
8. One of the defects of simple primary cells is polarization. Explain how this defect prevents current flow in a cell.   (2 marks)
9. Figure 5 shows a ray of light incident on a right-angled glass prism.
    
                                    Figure 5
   Given that the refractive index of glass is 1.5, draw in the figure above the path followed by the ray of light until it emerges from the prism.
    (2 marks)
10. Figure 6 (drawn to scale) shows wave fronts approaching an obstacle with an aperture.
    
          Figure 6
    Draw the wave fronts as they appear after passing through the aperture.   (1 mark)
11. A compass needle is placed below a current carrying conductor as shown in figure 7.
    
    Indicate on the diagram the direction of the current.   (1 mark)
12. The target of modern X-ray tubes are made to rotate. Explain
13. State two reasons why gamma rays from a radioactive source are preferred to X-rays from an X- rays tube in sterilization of medical equipment.
14. The following reactions are part of a radioactive series.
    
    Identify the radiation X
15. Current is made to flow through a resistance wire for some time. Explain why temperature of the wire rises (2 marks)

Section B (55 marks)

Attempt all question in this section in the spaces provided.

16.  
    1. Distinguish between a real and a virtual image       (1 mark)
    2. Figure 8 shows scale drawing of a window frame and its image produced on a screen by a convex  lens.
       
       1. State the nature of the mage formed   (1 mark)
       2. Determine the linear magnification of the image    (2 marks)
    3. The image of the frame was produced 500 mm from the lens.
       Determine:
       1. The distance of the actual frame from the lens   (2 marks)
       2. The focal length of the lens   (3 marks)
    4. A student finds that at a distance of 25cm, the words in a book look blurred.
       1. State the eye defect the student is suffering from   (1 mark)
       2. Name the type of lens that can be used to correct the above defect.   (1 mark)
17.  
    1. Figure 9 shows ultra-violet light striking a polished zinc plate on a negatively charged gold leaf electroscope.  
       
                  Figure 9
       Explain the following observations.
       1. The leaf of the electroscope falls.     (2 marks)
       2. When the same experiment was repeated with a positively charged electroscope the leaf did not fall.      (2 marks)
    2. State two factors which determine the speed of photoelectrons emitted from a metal surface.     (2 marks)
    3. Figure 10 shows a graph of the square of the maximum velocity (V_max)² of the emitted photoelectrons against the frequency (f) of the radiation causing photo-electricity on a clean zinc plate
       
       1. Determine the slope of the graph.    (2 marks)
       2. Given that the equation of the line is (V_max)² = 2h f − 2h f_o, where m_e = 9.11x10⁻³¹ kg.
                                                                                    m_e      m_e
          From the graph determine the:
          1. Minimum frequency of the radiation that will cause emission of electrons from the zinc surface.    (1 mark)
          2. Planck's constant.     (2 marks)
          3. Minimum amount of energy required to just emit electrons from the zinc surface.      (2 marks)
18.  
    1. Figure 11 shows two magnets A and B suspended by springs in two separate coils connected as shown.
       
                                     Figure 11
       1. Magnet A is set to oscillate in the coil. State the observation made on magnet B.   (1 mark)
       2. Explain the observation in (i) above.     (3 marks)
    2. State Faraday's law of electromagnetic induction.  (1 mark)
    3. Figure 12 shows two coils wound on a laminated soft iron core. It is connected to a 300V mains supply.
       
                           Figure 12
       1. Identify the type of the transformer in figure 12.    (1 mark)
       2. The transformer in figure 12 loses 20% of the input energy into heat per second. Determine the maximum current measured on the ammeter, if the input current is 2A.     (3 marks)
       3. Explain how energy losses in the transformer in figure 12 are minimized by having a soft iron core.  (2 marks)
19.  
    1. A p-type semiconductor is made by doping a pure silicon crystal with few boron impurity atoms. Describe how this p-type is formed.
       (2 marks)
    2. Figure 13 shows an incomplete diagram of a centre tap full-wave rectifier.
       
                        Figure 13
       1. Complete the diagram by placing the missing components using their circuit symbols     (2 marks)
       2. Figure 14 shows how the input voltage of the full wave rectifier in figure 13 varies with time.
          
                             Figure 14
          Sketch, in the axes provided, a graph showing the output voltage of the rectifier in gure 13 varies with time.   (1 mark)
    3. Figure 15 shows a circuit having the following components: a 20V p.d source, a voltmeter, three switches S₁, S₂ and S₃ and two capacitors C₁ and C₂ of capacitance 13μF and 8uF respectively.
       
                                             Figure 15
    4. 
       
       1. Determine the charge on C₁ when switches S₂ and S₃ are closed while S₁ is open.   (3 marks)
       2. After some time S₃ is opened and both S₁ and S₂ are closed. Find the maximum voltage, V recorded by the voltmeter    (3 marks)
20.  
    1. A.G.M tube may register some effect in the absence of a radioactive source. Explain this observation and state one cause. (2 marks)
       Explanation:
       Cause:
    2. A radioactive element A of half-life 31 days decays to element B. A sample of A of mass 32g is kept in a container. Assuming B is stable, calculate the mass of B that will be in the container after 124 days.   (3 marks)
    3. Figure 16 shows the features of an x-ray tube.
       
                  Figure 16
       1. Give a reason why thick copper block is used at the anode.      (1 mark)
       2. State how the energy of the X-rays can be increased.     (1 mark)
       3. X-ray tube operates at 100kV between the cathode and the anode. Calculate the maximum energy of the X-ray photons produced.
          (charge of an electron,e=1.6×10⁻¹⁹C).   (2 marks)

MARKING SCHEME

Section A (25 marks)

1.  
   • Image becomes dimmer/less bright...
   • Since light spreads over a larger area..
2. Negative
3.  
   • Power loss due since resistance of the cables is minimal...
   • They are less costly      (2 marks)
4.   
   
   correct pattern and direction of magnetic field 
5.  
   
6. 100 = 240 X I  ✓1
   I  = 0.4167A✓1
7.  
   • Speed of sound increases.  ✓1
   • since air becomess less dense   
8. Polarization terminates cell reaction✓1 due to accumulation of hydrogen gas around the positive electrode✓1
9.  
   
10.  
    
    • no change in wavelength    ✓1
    • straight waves with slight, bends at the tip   ✓1
11.  
    
12. Rotation changes the point of impact. ✓1 hence reducing wear and tear/enables longer scans to be done, and at higher doses/allows heat to be spread over a larger area...✓1
13.  
    • Sources of gamma rays are more portable...  ✓1
    • No power requirement during production of gamma rays,  ✓1
14. Alpha particle.... ✓1
15. As electrons flow through the wire, they collide with ions/atoms/.... impurities, in the wire which cause the ions to vibrate ✓1Electrons.... therefore lose their kinetic energy in form of heat, hence increase in / temperature.  ✓1
16.  
    1. A real image is that which forms on the screen by intersection of real rays WHILE virtual image is that which cannot be formed on a screen due to intersection of apparent/virtual rays..  ✓1
    2.  
       1. Real
       2. m = ^v/_u 
             = 200  ✓1
                600
             = ¹/₃   ✓1
    3.  
       1. ¹/₃ =  ⁵⁰⁰/_u  ✓1 ⇒ u = 3 × 500 = 1500mm ✓1
       2. ¹/f  = ¹/_u + ¹/_v =
          ¹/_f = ¹/₁₅₀₀ + ¹/500 
          f = 1500 × 500  
                1500 + 500
            =375mm
    4.  
       1. Long sightedness // hypermetropia ✓1
       2. Converging/convex lens   ✓1
17.  
    1.  
       1. U.V.. radiation dislodges electrons from the zinc plate  ✓1 making it positive. The zinc plate thus attracts electrons from the leaf, hence neutralising the electroscope.  ✓1
       2. UV radiation dislodges electrons from the zinc plate  ✓1 but are immediately attracted by the positive charges on the electroscope. ✓1
    2.  
       • Workfunction of the metal,  ✓1
       • Energy/frequency/wavelength of the radiation.   ✓1
    3.  
       1. slope =   (5 − 0.7)X10¹¹         ✓1
                       (7.5 − 4.5)x10¹⁴ 
                      = 1.433X10⁻³m²s⁻¹
       2.  
          1. 4.0X10¹⁴Hz    ✓1    (graph must be extrapolated)....
          2. 1.433X10⁻³      =        2h              ✓1  
                                         9.11X10⁻³¹
                                     = 6.527X10⁻³⁵ Js   ✓1 
          3. E = hf
                = 6.527 X 10⁻³⁴ X 4.0X10¹⁴  ✓1  
                = 2.611X10^-19 J ✓1 
18.  
    1.  
       1. The magnet oscillates vertically at the frequency of A   ✓1 
       2. Oscillating A produces a changing magnetic flux in the coil thus an ✓1  a.c current is induced, causing an alternating magnetic effect on B ✓1  making it to oscillate. Induced current opposes the change producing it. reducing both the frequency of A and the magnitude of the induced current hence magnetic effect on B reduces at the frequency of A. ✓   (I mark)
    2.  The magnitude of the induced electromotive force is directly proportional to the rate of change of the magnetic flux linkage.   ✓1 
    3.  
       1. Step-down transformer
       2. l_sN_s = l_pN_p.   ✓1 
          I_s x 600 = (2x1000) 0.8   ✓1  
          l_s = 2667A   ✓1 
       3. The laminations are thin, thereby enhancing/increasing the resistance in each lamination. ✓1  This reduces the eddy current in each lamination, and hence the net. eddy current is reduced. ✓1 
19.  
    1. All three electrons in the outermost energy level of Boron bond with the neighbouring Silicon atoms leaving Silicon with an extra unbonded electron. ✓1  The missing electron on Boron creates a vacancy/hole as th majority charge carrier responsible for conduction. ✓1  
    2.  
       1. 
          −
       2.  
          
    3.  
       1. Q = CV  ✓1
          Q = 13 X 10⁻⁶ X 20   ✓1
              = 2.6 X10⁻⁴ C.  ✓1
       2. Q = CV  ✓1
          2.6X10⁻⁴ = (8+13) x 10⁻⁶ × V  ✓1
          V = 12.38v  ✓1
20.  
    1. Explanation:   to background radiation.   ✓1
       Cause:  Radioactive substances in air, cosmic rays, sun's radiation, natural and artificial radioisotopes (any).  ✓1
    2. N =. N₀(0.5)ⁿ  ✓1
       N = 32(0.5)^124/31  ✓1
       N = 29✓
    3.  
       1.  
          • Copper is a good conductor of heat therefore easily dissipates heat  away
            OR
          • Thick copper block is to provide a large surface area through which more heat is dissipated away
       2. By increasing the accelerating/anode potential.  ✓1
       3. Energy = e V
                       = 1.6X10^-19 X 100,000   ✓1
                       = 1.6X10^-14J    ✓1