Physics P2 Questions and Answers - Wisdom Pre-Mock Form 4 Exams 2021/2022

« Previous Topic
Physics P1 Questions and Answers - Wisdom Pre-Mock Form 4 Exams 2021/2022

Next Topic »
Physics P3 Questions, Answers and Confidential - Wisdom Pre-Mock Form 4 Exams 2021/2022

Download PDF for future reference Get on Whatsapp for 50/-

INSTRUCTION TO CANDIDATES

Write your name, index number in the spaces provided.
This paper consists of TWO sections: A and B.
Answer ALL questions in section A and B in the spaces provided.
ALL workings MUST be clearly shown.
Mathematical tables and electronic calculators may be used.

For Examiner’s Use Only

Section	Question	Maximum score	Candidate’s score
A	1 – 12	25
B	13 14 15 16	16 14 14 11
	Total	80

QUESTIONS

The figure below shows an object O in front of a curved mirror M.
1. On the figure, locate the image formed. (3 marks)
State two ways of decreasing the strength of an electromagnet. (2 marks)
State one disadvantage of using a convex mirror as a driving mirror. (1 mark)
State two factors that affect the resistivity of an electrical conductor. (2 marks)
A coin is placed at the bottom of a beaker containing a transparent liquid. When viewed from the top, the coin appears nearer the surface than it actually is. Explain the observation. (2 marks)
The figure below shows a wave in progress.

Determine the
1. Amplitude (1 mark) …………………………………………………………
2. Frequency (2 marks) ………………………………………………………
3. On the figure above, draw how the wave would appear if the period and amplitude is halved. (1 mark)
A ferromagnetic material is being magnetized by single stroking method. On the axes provided, sketch a graph to show how the strength of the magnet being created varies with the number of strokes (1 mark)
Figure 4 shows a conductor carrying current placed in the magnetic field and moves in the direction shown

Identify the polarities of X and Y. (2 marks)
X…………………………………………………………………………………………………
Y…………………………………………………………………………………………………
A boy standing in front of a cliff blows a while and hears echo after 0.5s. He then makes 17metres further away from the cliff and blows the whistle again. He now hears the echo after 6.0 s. determined the speed of the sound. (3 marks)
1. What is meant by the term electric current? (1 mark)
2. 0.25A of current passes through a point in a conductor in 3.5 minutes. Calculate the amount of charge passing through the point in this time. (2 marks)
3. An unmagnetized steel rod is clamped facing North-South direction and then hammered repeatedly for some time. When tested, it is found to be magnetized. Explain this observation (2 marks)

SECTION II (55 MARKS)

1. State Ohm’s law. (1 mark)
2. The graph below shows results obtained in an experiment to determine the e.m.f.(E) and the internal resistance, r, of a cell.
  
  Given that the equation of the graph is E = r + 1
  V R
  Use the graph to determine the values of:-
  1. E (2 marks)
  2. r (3 marks)
3. The figure below shows five resistors and a source of voltage of 6V.
  1. Find the effective resistance of the circuit. (2 marks)
  2. Calculate the current through 5Ω. (3 marks)
  3. What is the p.d across 2Ω. (3 marks)
  4. Calculate the current through 1Ω. (2 marks)
1. In object is placed 30cm in front of a thin converging lens of focal length 20cm. The set up is represented in the figure.
  1. On the same figure construct a ray diagram to locate the position of the image. (3 marks)
  2. Determine the magnification produced. (2 marks)
2. An object 6cm tall is placed 40cm from a convex lens of focal length 50cm. Find the position of the image. (3 marks)
3. State two differences between the human eye and the camera. (2 marks)
4. The figure below shows an eye defect.
  1. Identify the defect. (1 mark)
  2. State the cause of the defect. (1 mark)
  3. Using a well labeled diagram, illustrate how the defect is corrected. (2 marks)
1. The figure below shows a pair of parallel plates of a capacitor connected to a Battery the upper plates is displaced slightly to the left.
  
  State with reason the effect of this movement of the capacitance (2 marks)
2. The figure below shows an electrical circuit with three capacitors A, B and C of Capacitance 4.0 μF, 5.0 μF and 3.0 μF respectively connected to a 12V battery
  
  Determine:
  1. The combined capacitance of the three capacitors (3 marks)
  2. The charge of the capacitor A (2 marks)
  3. The potential difference across the capacitor B (2 marks)
3. A positively charged sphere is suspended by an insulating thread. A negatively charged conductor is suspended near it. The conductor is first attracted, after touching the sphere it is repelled. Explain this observation. (2 marks)
4. A 2μF capacitor is charged to a potential of 200V, the supply is disconnected. The capacitor is then connected to another uncharged capacitor. The p.d across the parallel arrangement is 80V. Find the capacitance of the second capacitor. (3 marks)
1. A single ray of light in incident on an equilateral glass position as shown in the figure below. Complete the diagram to show the path of light through and out of the position.(critical angle of glass = 420) (3 marks)
2. State two (2) conditions necessary for total internal reflection (2 marks)
3. 1. Figure below shows an object O at the bottom of a beaker full of a liquid. An observer above the beaker sees its image at point X inside a liquid.
    
    Determine the refractive index of the liquid. (3 marks)
  2. Define the term critical angle(c) of a medium. (1 mark)
4. State two uses of optical fibre. (2 marks)

MARKING SCHEME

The figure below shows an object O in front of a curved mirror M.
1. On the figure, locate the image formed. (3 marks)
State two ways of decreasing the strength of an electromagnet. (2 marks)
- decreasing the amount of current
- decreasing the number of turns in the coil
- increasing the length of solenoid
State one disadvantage of using a convex mirror as a driving mirror. (1 mark)
- doess not give the actual distance of the vehicle behind
State two factors that affect the resistivity of an electrical conductor. (2 marks)
- resistance of the material
- cross sectional area of the conductor
- the length of the conductor
A coin is placed at the bottom of a beaker containing a transparent liquid. When viewed from the top, the coin appears nearer the surface than it actually is. Explain the observation. (2 marks)
- this is due to refraction of light. As a ray of light from the coin will undergo refraction as it moves from denser medium (water) to lesss dence medium (air)
The figure below shows a wave in progress.

Determine the
1. Amplitude (1 mark)
  - 2cm
2. Frequency (2 marks)
  - f = 1
    T
    T = 85
    f = 1
    8
    =0.125HZ
3. On the figure above, draw how the wave would appear if the period and amplitude is halved. (1 mark)
  - SEE ABOVE
A ferromagnetic material is being magnetized by single stroking method. On the axes provided, sketch a graph to show how the strength of the magnet being created varies with the number of strokes (1 mark)
Figure 4 shows a conductor carrying current placed in the magnetic field and moves in the direction shown

Identify the polarities of X and Y. (2 marks)
X North pole
Y South pole
accept north nad south
A boy standing in front of a cliff blows a whistle and hears echo after 0.5s. He then makes 17metres further away from the cliff and blows the whistle again. He now hears the echo after 6.0 s. determined the speed of the sound. (3 marks)
1. What is meant by the term electric current? (1 mark)
  - rate of flow of electrical current
2. 0.25A of current passes through a point in a conductor in 3.5 minutes. Calculate the amount of charge passing through the point in this time. (2 marks)
  - Q = It
    Q = 0.25 × 3.5 × 60
    =52.5C
3. An unmagnetized steel rod is clamped facing North-South direction and then hammered repeatedly for some time. When tested, it is found to be magnetized. Explain this observation (2 marks)
  - byy hammering the dipetes vibrate
    the earth's magnetic field then aligns the dipetes in north-south direction making the steel magnetised

SECTION II (55 MARKS)

1. State Ohm’s law. (1 mark)
  - the current flowing through a conductor is directly proportional to the potential difference across it providing the temperature and other physical conditions are kept constant.
2. The graph below shows results obtained in an experiment to determine the e.m.f.(E) and the internal resistance, r, of a cell.
  
  Given that the equation of the graph is E = r + 1
  V R
  Use the graph to determine the values of:-
  1. E (2 marks)
    - 1 = r + 1
      V RE E
      1 = 1(r) + 1
      V R(E) E
      y = mx + c
      1 = y-intercept
      E
      1 = 0.65v^-1
      E
      E = 1
      0.65v^-1
      = 1.538v
  2. r (3 marks)
    - 1 = r(1) + 1
      v E R E
      y = mx + c
      r = gradient
      E
      r = slope × E
      slope = 2.5 - 1.0
      2.35 - 0.40
      = 1.5
      1.95
      slope = 0.7692v^-1/Ω^-1
      r = 1.538 × 0.7692
      r = 1.1830Ω
3. The figure below shows five resistors and a source of voltage of 6V.
  1. Find the effective resistance of the circuit. (2 marks)
    - 2 × 3 = 6 = 1.2Ω
      2 + 3 5
      1.2Ω + 4Ω = 5.2Ω
      5.2 × 1 = 5.2 = 0.8387Ω
      5.2 + 1 6.2
      0.8387Ω + 5Ω
      RE = 5.8372Ω
  2. Calculate the current through 5Ω. (3 marks)
    - I = V
      R
      I₅_Ω = 6
      5.8372
      I₅_Ω = 1.028A
  3. What is the p.d across 2Ω. (3 marks)
  4. Calculate the current through 1Ω. (2 marks)
    - I₁_Ω = 5.2 × 1.028
      6.2
      = 0.8622A
      or
      I₁_Ω = 0.8622
      1
      = 0.8622A
1. In object is placed 30cm in front of a thin converging lens of focal length 20cm. The set up is represented in the figure.
  1. On the same figure construct a ray diagram to locate the position of the image. (3 marks)
    - SEE ABOVE
  2. Determine the magnification produced. (2 marks)
    - m = hI
      ho
      = 2.2
      1.3
      m = 1.692
      or
      m = v
      u
      = 3.0
      1.8
      = 1.667
2. An object 6cm tall is placed 40cm from a convex lens of focal length 50cm. Find the position of the image. (3 marks)
  f = 50cm
  u = 40cm
  1 = 1 + 1
  f v u
  1 = 1 + 1
  50 v 40
  1 = 1 + 1
  v 50 40
  1 = -1
  v 200
  v = -200cm
3. State two differences between the human eye and the camera. (2 marks)
  - the focal length of the eye lens is variable while that of the camera is fixed
  - cameras(with zoom length) have variable image distance while the eye has a constant image distance
    any other suitable answer
4. The figure below shows an eye defect.
  1. Identify the defect. (1 mark)
    - long sight / hypermetrophia
  2. State the cause of the defect. (1 mark)
    - eyeball being too short
    - focal length of the lens being too long
  3. Using a well labeled diagram, illustrate how the defect is corrected. (2 marks)
1. The figure below shows a pair of parallel plates of a capacitor connected to a Battery the upper plates is displaced slightly to the left.
  
  State with reason the effect of this movement of the capacitance (2 marks)
  - capacitance decreases
  - moving the upper plates to the left decreases the area of overlap
2. The figure below shows an electrical circuit with three capacitors A, B and C of Capacitance 4.0 μF, 5.0 μF and 3.0 μF respectively connected to a 12V battery
  
  Determine:
  1. The combined capacitance of the three capacitors (3 marks)
    - 5 + 3 = 8μF
      C_T = C1C2
      C2 + C1
      C_T = 8 × 4
      8 + 4
      =32
      12
      C_T = 2.667μF
  2. The charge of the capacitor A (2 marks)
    - Q = Cv
      =2.667 × 10^-6 × 12
      =32.00 × 10^-6
      or
      Q = 32Cμ
  3. The potential difference across the capacitor B (2 marks)
    - V8μf = 32 × 10^-6
      8 × 10^-6
      = 4v
      or
      V₈_μf = V₅_μf = 4V
3. A positively charged sphere is suspended by an insulating thread. A negatively charged conductor is suspended near it. The conductor is first attracted, after touching the sphere it is repelled. Explain this observation. (2 marks)
  - attraction is asa a result of the two having unlike charges
    on touching the positive charge on the sphere are neutralized it then acquire negatively charges which then refuels the negatively cherged conductor
4. A 2μF capacitor is charged to a potential of 200V, the supply is disconnected. The capacitor is then connected to another uncharged capacitor. The p.d across the parallel arrangement is 80V. Find the capacitance of the second capacitor. (3 marks)
  - Qα = CV
    =2 × 10^-6 × 200
    =400 μC
    Qα = Q2μ + Qe
    Qemf = 2 × 80 × 10^-6
    = 160 × 10^-6
    =160 μC
    Qc = (400 - 160) μC
    = 240 μC
    C = Q
    v
    =240 × 10^-6
    80
    = 3 × 10^-6F
    c = 3 μC
1. A single ray of light in incident on an equilateral glass position as shown in the figure below. Complete the diagram to show the path of light through and out of the position.(critical angle of glass = 420) (3 marks)
2. State two (2) conditions necessary for total internal reflection (2 marks)
  - the angle of incidence in the optically denser medium must be greater than the critical
  - ray of light must be travelling from oficially denser medium to optically less denser medium
3. 1. Figure below shows an object O at the bottom of a beaker full of a liquid. An observer above the beaker sees its image at point X inside a liquid.
    
    Determine the refractive index of the liquid. (3 marks)
    - n = real depth
      apparent depth
      n = 40
      30
      =1.333
  2. Define the term critical angle(c) of a medium. (1 mark)
    - the angle of incidence in the optically denser medium refraction is 90º in the less dense medium
4. State two uses of optical fibre. (2 marks)
  - used in medicine to view the internal organs
  - used in telecommunications