Physics Paper 2 Questions and Answers - Kassu Jet Pre Mocks 2022

Instructions to candidates

• Write your name, admission number, class, signature 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)
Attempt all the questions in the spaces provided

1. State the laws of reflection of light (2 marks)
2. State the two advantages of optical fibre over the ordinary cable (2 marks)
3. Derive the expression for the total electrical energy converted into heat in a wire of resistance, R when a current, I is maintained through it for a time,t (3 marks)
4. A driver looked into his side mirror and saw a diminished image of a car behind him
   1. State the type of mirror the side mirror is made of (1 mark)
   2. State two reasons why (a) above is preferred as side mirror (2 marks)
   3. Define focal length of concave mirror (1 mark)
5. State the basic law of electrostatics (1 mark)
6. The diagram below shows the different parts of a loud speaker
   
   State the role of the current from the amplifier (2 marks)
7.                                
   1. You are provided with two iron bars, x and y, one is magnetized and the other is not
      Explain how you would identify the magnetized bar without using a magnet (2 marks)
   2. The figure below shows a set-up used to make a magnet
      
      
      1. Explain why soft iron is used (1 mark)
      2. Complete the diagram to show how a battery should be connected at A so that the polarities of P and Q are south and North respectively (1 mark)
8. A boy strikes a railway line with a hammer A railway worker 60m away hears two sounds, one from the railway line and the other from air If the time interval between the sounds is 016 seconds, and the average speed of the sound in air is 320 m/s Determine the speed of sound in the rail (3 marks)
9.                            
   1. Define electric current (1 mark)
   2. A current of 3A passes through bulb B for 3 minutes 45 seconds Determine the quantity of change through B (2 marks)
10. State one way in which radio waves can be detected (1 mark)
    SECTION B (55 MARKS)
    Attempt all the question in the spaces provided
11.                        
    1. State Faraday’s law of electromagnetic induction (1 mark)
    2. A bar magnet is moved into a coil of insulated copper wire connected to a centre-zero galvanometer as shown below
       
       
       1. Show on the diagram, the direction of induced current in the coil (1 mark)
       2. State and explain what is observed on the galvanometer when the north pole of the magnet is moved into and then withdrawn from the coil (3 marks)
    3. A transformer has 1000 turns in the primary and 40 turns in the secondary winding The alternating emf connected to the primary is 240V and the current is 04A
       Determine:
       1. The secondary voltage (emf) (2 marks)
       2. The power in the secondary, if the transformer is 90% efficient (3 marks)
12.                                
    1. State any two ways of decreasing the capacitance of a parallel-plate capacitor (2 marks)
    2. A metallic body shaped as shown below is positively charged and insulated from the ground
       
       Show on the figure the charge distribution on the conductor (1 mark)
    3. The figure below shows three capacitors A, B and C connected to a battery of emf 120V and zero internal resistance
       
       Determine:
       1. The effective capacitance of the circuit (3 marks)
       2. The pd across the 12 μF capacitor (3 marks)
       3. Charge stored in the 1 μF capacitor (2 marks)
13.                                        
    1. State Ohm’s law (1 mark)
    2. The cell in figure has an emf of 26V and negligible internal resistance
       
       Determine the:
       1. Total resistance in the circuit (2 marks)
       2. Current in the circuit (2 marks)
       3. Reading on the voltmeter (2 marks)
    3. The graph below shows how the voltage, V, varies with the current, I for a filament lamp
       
       
       1. From the graph, determine the resistance of the lamp when a current of 5A flows (3 marks)
       2. State with a reason whether the device is ohmic or non-ohmic (2 marks)
14.        
    1.                                         
       1. Define the term lens (1 mark)
       2.                            
          1. The figure below shows a convex lens with an object before it Draw rays to identify the position of image formed
             
          2. State one device in which such a set-up is used (1 mark)
    2. A lens forms an image that is four times the size of the object on a screen The distance between the object and the screen is 150 cm when the image is sharply focused
       1. State with reason the type of lens that was used (2 marks)
       2. Determine the focal length of the lens (4 marks)
15.                                
    1. Distinguish between longitudinal and transverse wave (1 mark)
    2. The figure below shows the displacement- time and displacement-distance graphs of a certain wave
       
       From the information above show that the speed of the wave = frequency X wavelength
       (c=f ג) (2 marks)
    3. Figure shows two speakers connected to an audio – frequency generator
       
       
       1. Give reason why the loudspeakers are connected to the same audio – frequency generator (1 mark)
       2. State and explain the observation made by an observer moving along the path PQ (2 marks)
       3. State the observations made if the frequency of the signal generator was increased (1 mark)
       4. Explain the observation made when the distance CO was increased (1 mark)
       5. If the distances S1P and S2P are 64m and 74m respectively Determine the frequency of the signal generator from the set up above given that P is the first constructive interference after the central order and the velocity of sound is 320m/s (3 marks)

MARKING SCHEME

SECTION A: (25 MARKS)
Attempt all the questions in the spaces provided

1. State the laws of reflection of light (2 marks)
   • the incident ray, reflected ray and the normal at the point of incidence all lie on the same plane surface
   • the angle of incidence equal to angle of reflection
2. State the two advantages of optical fibre over the ordinary cable (2 marks)
   • they have a higher carrying capacity
   • they are lighter
3. Derive the expression for the total electrical energy converted into heat in a wire of resistance, R when a current, I is maintained through it for a time,t (3 marks)
   • work done  = QV but 4 = it and v = IR
     IT x IR
     I²RT
4. A driver looked into his side mirror and saw a diminished image of a car behind him
   1. State the type of mirror the side mirror is made of (1 mark)
      • convex mirror
   2. State two reasons why (a) above is preferred as side mirror (2 marks)
      • they produce upright images regardles of object distance
      • they have a wider field of view
   3. Define focal length of concave mirror (1 mark)
      • distance from the pole of mirror to the principal focus
5. State the basic law of electrostatics (1 mark)
   • unlike charges attract while like charges repel
6. The diagram below shows the different parts of a loud speaker
   
   State the role of the current from the amplifier (2 marks)
   • causing the coil to move to and fro due to varying current;  making diagram vibrate to and fro producing sound
7.                                
   1. You are provided with two iron bars, x and y, one is magnetized and the other is not
      Explain how you would identify the magnetized bar without using a magnet (2 marks)
      • suspend the two bars x and y using a string
      • allow them to freely swing, the one that is magnetized will offer a point turn rest in N-S chain of earth's magnetic axis while the unmagnetised will continue swinging
   2. The figure below shows a set-up used to make a magnet
      
      
      1. Explain why soft iron is used (1 mark)
         • easily magnetised and demagnetised
      2. Complete the diagram to show how a battery should be connected at A so that the polarities of P and Q are south and North respectively (1 mark)
8. A boy strikes a railway line with a hammer A railway worker 60m away hears two sounds, one from the railway line and the other from air If the time interval between the sounds is 016 seconds, and the average speed of the sound in air is 320 m/s Determine the speed of sound in the rail (3 marks)
   • v = 2x (echo)
            t
     320 = 60/t
     t = 60/320 = 0.1815 / 0.195
     t_solid = 0.19 - 0.16 = 0.035
     speed = 60/0.03 = 200 m/s
9.                            
   1. Define electric current (1 mark)
      • rate of flow of charge or flow of charge per unit time
        
   2. A current of 3A passes through bulb B for 3 minutes 45 seconds Determine the quantity of change through B (2 marks)
      • Q = It
        3 x (3 x 60 + 45)
        = 675 c
10. State one way in which radio waves can be detected (1 mark)
    • use of earphones
      SECTION B (55 MARKS)
      Attempt all the question in the spaces provided
11.                        
    1. State Faraday’s law of electromagnetic induction (1 mark)
       • the magnitude (size) of an inducor is directly proportional to the rate of change of magnetic flux linkage
    2. A bar magnet is moved into a coil of insulated copper wire connected to a centre-zero galvanometer as shown below
       
       
       1. Show on the diagram, the direction of induced current in the coil (1 mark)
       2. State and explain what is observed on the galvanometer when the north pole of the magnet is moved into and then withdrawn from the coil (3 marks)
          • the galvometer deflects in the direction of induced current
          • when withdrawn, the direction of incidence current reverses such as to oppose (attract) N-pole leaving this coil. Deflection of galvometer reverses
    3. A transformer has 1000 turns in the primary and 40 turns in the secondary winding The alternating emf connected to the primary is 240V and the current is 04A
       Determine:
       1. The secondary voltage (emf) (2 marks)
          • Vs = Ns
            Vp    Np
              Vs = 40
            240   1000
            Vs = 240 x 40 
                      1000
            = 9.6 V
       2. The power in the secondary, if the transformer is 90% efficient (3 marks)
          ans = 108 W
12.                                
    1. State any two ways of decreasing the capacitance of a parallel-plate capacitor (2 marks)
       • decrease in the area of overlap between places
       • increase in the distance of departion between plates
    2. A metallic body shaped as shown below is positively charged and insulated from the ground
       
       Show on the figure the charge distribution on the conductor (1 mark)
    3. The figure below shows three capacitors A, B and C connected to a battery of emf 120V and zero internal resistance
       
       Determine:
       1. The effective capacitance of the circuit (3 marks)
          • parallel 1 + 2 = 3uf
            series  12 x 3 = 36 = 2.4 uf
                        12 + 3   15
       2. The pd across the 12 μF capacitor (3 marks)
          • = cv = 2.4 uf x 12 = 28.8 uf
            v = q = 28.8 uf = 2.4 v
                  c     12 uf
       3. Charge stored in the 1 μF capacitor (2 marks)
          • 12 - 2.4 = 9.6
            Q = CV = 1 x 9.6 = 9.6 Mc
13.                                        
    1. State Ohm’s law (1 mark)
       • current flowing through a current -carrying conductor is directly proportional to the potential difference accross its ends, p..... temperature and other physical conditions are kept constant
    2. The cell in figure has an emf of 26V and negligible internal resistance
       
       Determine the:
       1. Total resistance in the circuit (2 marks)
          • parallel = 30 x 30 = 15Ω
                           30 + 30
            series  10 + 15  = 25Ω
       2. Current in the circuit (2 marks)
          I = V1/R1 = 2.6/25 = 0.104 A
       3. Reading on the voltmeter (2 marks)
          • V = IR
            = 0.104 x 10= 1.04V
    3. The graph below shows how the voltage, V, varies with the current, I for a filament lamp
       
       
       1. From the graph, determine the resistance of the lamp when a current of 5A flows (3 marks)
          • At I ; V = 0.4 v
            v = IR
            0.5 = 5R
            R = 0.4 = 0.08Ω
                    5
       2. State with a reason whether the device is ohmic or non-ohmic (2 marks)
          • non-ohmic ; resistance varies with time
14.        
    1.                                         
       1. Define the term lens (1 mark)
          • is a transparent material with at least one curved surface that operates on the principle of refraction
       2.                            
          1. The figure below shows a convex lens with an object before it Draw rays to identify the position of image formed
             
          2. State one device in which such a set-up is used (1 mark)
             • search ligher
             • spot light
    2. A lens forms an image that is four times the size of the object on a screen The distance between the object and the screen is 150 cm when the image is sharply focused
       1. State with reason the type of lens that was used (2 marks)
          • conves lens (diverging). A magnifies image is foward on scan
       2. Determine the focal length of the lens (4 marks) = 24 cm
15.                                
    1. Distinguish between longitudinal and transverse wave (1 mark)
       • longitudinal waves are those whose particle vibration is parallel to the wave travel while traverse are those wave particles vibration is perpendicular to the wave travel
    2. The figure below shows the displacement- time and displacement-distance graphs of a certain wave
       
       From the information above show that the speed of the wave = frequency X wavelength
       (c=f ג) (2 marks)
       • speed = distance travelled = x but T  = 1/f
                         time taken             T
         v = x/T = fx
    3. Figure shows two speakers connected to an audio – frequency generator
       
       
       1. Give reason why the loudspeakers are connected to the same audio – frequency generator (1 mark)
          • to produce coherent sound waves/waves of same wavelength frequency
       2. State and explain the observation made by an observer moving along the path PQ (2 marks)
          • the observer will hear instances of loud and soft sound 
          • loud sound is due to constructive interfacae , soft sound is due to destructive interface
       3. State the observations made if the frequency of the signal generator was increased (1 mark)
          • distance between loud an dsoft sound decreases more soft and lound sounds heard
       4. Explain the observation made when the distance CO was increased (1 mark)
          • distance between the sounds(bangs) increases
       5. If the distances S1P and S2P are 64m and 74m respectively Determine the frequency of the signal generator from the set up above given that P is the first constructive interference after the central order and the velocity of sound is 320m/s (3 marks) ans = 320 Hz