Physics Paper 2 Questions and Answers - Sunrise 2 Evaluation Mock Exams 2022

Instructions to candidates

• Write your name, admission number, class and date in the spaces provided at the top of the page
• This paper consists of two sections A and B
• Answer all the questions in the two sections in the spaces provided after each question
• All working must be clearly shown
• Electronic calculators, mathematical tables may be used
• All numerical answers should be expressed in the decimal notations

QUESTIONS

SECTION A: (25 MARKS)

1. Differentiate between primary and secondary cells (1mk)
2. The diagram in figure 1 below shows the displacement against time for a wave whose wavelength is 40mm
   
   Determine the velocity of the wave (3mks)
3. The figure 2 below shows a thin wire connected to a charge generator and placed close to a candle flame
   
   Explain why the candle flame is deflected as shown (2mks)
4. What is thermionic emission? (1 mk)
5. Ultraviolet radiation incident on a zinc plate releases electrons from the zinc surface The energy of each incident proton is 54eV Zinc has a work function of 43eV
   1. State the name given to this effect (1 mk)
   2. What is meant by work function of the metal? (1 mk)
   3. An electron is emitted from the surface of zinc Calculate the maximum kinetic energy of the electron in Joules (2 mks)
6. A vibrating tuning fork of frequency 512Hz was brought close to two test tubes X and Y
   With water levels as shown in fig 3
   Fig 3
   
   It was observed that loud sound is produced in test tube X but not in Y Explain this observation (2mks)
7. The chart below shows an arrangement of different parts of the electromagnetic spectrum
   

   Radio

   A

   Visible

   Ultra-violet

   X-rays

   Gamma-Rays

   Name the radiation represented by A (1mk)
8. The figure 4 below shows a container loader which uses electromagnet to offload containers from a ship
   
   
   1. Why should the container be made of iron (1 mrk)
   2. State two ways in which the loader can be made to lift a heavier container (2 mrks)
9. The figure below shows an object O and it’s image I formed by a concave mirror The diagram is drawn to scale
   
   Using a suitable ray, determine the focal length (f) and the radius of curvature (r) of the mirror (3 marks)
   f cm
   r cm
10. State two differences between pinhole camera and the human eye (2 marks)
11. Give a reason why soft iron is used as a core of the coil of an electric bell (1 mark)
12. State two uses of gold leaf electroscope (2 marks)

SECTION B: (55 MARKS)

13.                        
    1. Define a resistor (1 mark)
    2. The figure below shows three resistors connected to 12v supply of internal resistance of 02Ω
       
       Calculate
       1. The effective resistance (3 marks)
       2. The total current in the circuit (2 marks)
       3. the current through the 4Ω resistance (3 marks)
    3. If the current flows for 2 minutes calculate the total energy dissipated (2 marks)
    4. State two applications of resistors in real life situation (2 marks)
14.                      
    1. Define the following terms
       1. Capacitor (1 mark)
       2. Capacitance (1 mark)
    2. Three capacitors are connected to a 10v battery
       
       Calculate
       1. The effective capacitance (3 marks)
       2. The total charge (3 marks)
    3. State three factors that determine the capacitance of a capacitor (3 marks)
15.              
    1.                  
       1. X- rays are used for detecting cracks inside metal beams; (i) State the type of the X- rays used (1mark)
       2. Give a reason for your answer in (i) above (1mark)
    2. Figure shows the features of an X- ray tube
       
       
       1. Name the parts labelled A and B (2marks)
          A
          B
       2. Explain how a change in the potential across P changes the intensity of the X- rays produced in the tube (2 marks)
       3. During the operation of the tube, the target becomes very hot Explain how this heat is caused (2 marks)
       4. What property of lead makes it suitable for use as shielding material?(1mark)
    3. ln a certain X- ray tube, the electrons are accelerated by a Pd of 12000V Assuming all the energy goes to produce X- rays, determine the frequency of the X- rays produced (Planck’s constant h= 662 x 10^-34 JS and charge on an electron, e = 16 x 10 ^-19C) (4marks)
16. A student connected a circuit as shown in figure 16 below hoping to produce a rectified out put
    
    
    1. Sketch the graph of the output on the CRO screen (2mark)
    2. Explain how the output above is produced (2marks)
    3. Name other two uses of a junction diode (2marks)
17.                      
    1. Thorium decays to protactinium by emission of a beta particle (β) as shown
       
       Determine the atomic and mass number of thorium
       Atomic number mass number (2marks)
    2. The figure 15 below shows the path taken by three radiations A,B and C from a radioactive source through an electric field
       
       Fig15
       1. Identify the radiation B (1 mark)
       2. Give a reason for the difference in deviation shown by A and C (2 marks)
    3. The table 1Below shows results obtained from a G-M tube when a radioactive sample was placed near it
       

       Time (min)	0	1	2	3	4	5	6
       Counts per (min)	1048	994	926	838	719	557	330
       Correct count

       1. Given that the background radiation was 30 counts per minute, fill in the blank spaces in the table (3mark)
       2. Draw a suitable graph on the grid provided (5marks)
          
          EMBED ExcelChart8 \s
       3. From the graph determine the half-life of the sample (1mark)

MARKING SCHEME

1. Primary cells cannot be recharged after use while secondary cells can be recharged after use.
2.  Λ = 4.0mm V = fλ
   f = 1/2x10^-3 = 500Hz
   1m = 1000mm = 4.0 x 10^-3m/s
   V = 500 x 4 x 10^-3 = 2.0m/s
3. The charged point conductor repels positive ions of the air while negative ions are attracted;
   The positive ions drift. Towards the flame forming an electric wind which drags the flame with it; 
4.                    
5.                                
6. In X the vibrating air column produces a complete note or overtone with large amplitude while in Y, the vibration of air in test Y does not
7. Infrared rays
8.                              
   1. Easy to magnetize
   2.                    
      • Increasing the amount of current in the electromagnet
      • Increasing the number of turns in the electromagnet. 
9.                  
   
   N/B: Use the students drawing, if correctly drawn, to obtain the values of r and f by measuring.
10. Camera does not have iris to control amount of light as in the eye.
    Pinhole no lens while eye as a lens
11. Easily magnetised& demagnetized
12. Compare charges
    Detect charge
13.                      
    1. That which opposes the flow of electrical current.
    2.                  
       1. Parallel ⇔1/R = 1/3 + 1/4
          = 4 +3 = 7/12
              12
          R = 12/7
          Series 12/7 + 2 = 12 + 14
                                           7
          = 3.86
       2. V = 1R
          ⇔ 12 = I x 3.86
          I = 12/3.86A
       3. Through 4Ω resistor
          = 3/7 of total
          = 3/7 x V/R
          = 3/7 x 12 x 7 A
          = 1.38A
          E = Pt = VIt
          = 12 x 1.38 x 2 x 60J
          = 1987.2J
    3.                  
    4. Radio circuit
       Heater coils
       Bulb filament
14.                  
    1.                    
       1. A device to store charge
       2. Ability of a capacitor to store charge.
    2.                
       1. Series1/c = 1/4 + 1/5 = 5 + 4 = 9/20
                                                 20
15.                      
    1. Parallel c = 20/9 + 3 = 20 + 9 = 29/9μf
                                                9
       = 3.2 x 10^-6F
    2. Q = cv
       = 29/9 x 10^-6 x 10
       = 32.2 x 10^-5C.
    3.                          
       • Type of dielectric material
       • Overlapping cross sectional area
       • Distance between the plates
16.                  
    1.                
       1. Hard X - rays
       2. Have high penetrating power
    2.                  
       1. A = Cathode rays / fast moving electrons
          B = Anode
       2. Change in heating current changes the number of electrons produced
       3. Kinetic energy of cathode rays is converted to heat energy.
       4. Has high density
    3. eV = hf
       1.6x 10^-19 x 12000 = 6.62 x 10^-34 x f
       f = 1.6 x 10^-19 x 12000
                 6.62 x 10^-34
       f = 2.9 x 10 18 Hz
17.                                              
    1.             
       
    2. During the first half –cycle D₁ is forward biased while D₂ is reverse biased. Hence , current takes the path A , D₁ RT .√
       During the next half –cycle, D₂ is forward biased while D₁ is reverse biased and the path of the current is BD₂RT.√
    3.                
       • Protects a circuit from damage √
       • As a switch √ Any 2
       • In charging a battery using solar panels.
18.                    
    1. atomic number 90√1mark mass number 234√1mark
    2.                  
       1. gamma rays.√1mark
       2. A are β particles which are negatively charged hence attracted to positively charged plate and are lighter than C hence more deviation compared to C which are α particles which are positively charged hence attracted to the negatively charged plate and are heavier hence less deviation.
    3.                              
       
       1.      
          

          correct account

          1018

          964

          896

          808

          689

          527

          300

       2.              
          
       3. half-life = 5.1min