46. Which of the following statements about a neutral atom is correct? The
- A. core is composed of electrons and protons
- B. number of electrons is equal to that of neutron
- C. number of neutrons is equal to that of protons
- D. number of protons is equal to that of electrons
47. Which of the following properties is not exhibited by sound waves
- A. Diffraction
- B. Polarization
- C. Interference
- D. Reflection
48. When ultraviolet light is incident on certain metallic p articles are emitted. These particles are called
- A. positrons
- B. protons
- C. photoelectrons
- D. photons
49. The graph above illustrates the variation of temperature θwith time (t) for a solid that is being heated. Which processes take place at segments P and Q respectively?
- A. Freezing and vaporization
- B. Evaporation and solidification
- C. Melting and boiling
- D. Condensation and evaporation
PHYSICS THEORY PAST QUESTIONS 2019 WITH SOLUTION
35. A ray of light travelling from a rectangular glass block of refractive index 1.5 into air strikes the block at an angle of incidence of 30. Calculate its angle of refraction.
- A. 48.6°
- B. 19.5°
- C. 20.0
- D. 45.0
- (a) (i) Define atomic spectra.
(ii) Differentiate between emission spectra and absorption spectra.
(b)
The diagram above illustrates an electron transition from energy level n = 3 to n = 1. Calculate the:
(i) energy of the photon
(ii) frequency of the photon
(ii) wavelength of the photon [h = 6.6 x 10−34J s, c = 3.0 x 1088 ms−1; 1 ev = 1.6 x 10−19 J]
c)(i)Differentiate between soft x-rays and hard x-rays (ii) Draw the circuit symbol for a p-n junction diode (iiii) Give the reason for doping a semiconductor material- (a) (i) Define atomic spectra.
2. You are provided with a stopwatch, a meter rule, a split cork, retort stand and clamp, a pendulum bob, a piece of thread, and other necessary apparatus.
- Place the retort stand on a laboratory stool. Clamp the split cork.
- Suspend the pendulum bob from the split cork such that the point of support Pof the bob is at height H = 100cm above the floor Q. The bob should not touch the floor and H should be kept constant throughout the experiment.
iii. Adjust the length of the thread such that the center A of the bob is at a height y= AQ= 20cm from the floor.
- Displace the bob such that it oscillates in a horizontal plane.
- Take the time t for 20 complete oscillations.
- Determine the period T of oscillation and evaluate T
vii. Repeat the procedure for four other values of y = 30cm, 40cm, 50cm, and 60cm. In each case, determine T and T.
viii. Tabulate the results.
- Plot a graph of T on the vertical axis and y on the horizontal axis, starting both axes from the origin (0,0).
- Determine the slope, s, of the graph and the intercept c on the vertical axis.
- If in this experiment SR= c, calculate R.
- State two precautions taken to ensure accurate results.
(b) i. The bob of a simple pendulum is displaced a small distance from the equilibrium position and then released to perform simple harmonic motion Identify where its:
(∝) kinetic energy is maximum
(β) acceleration is maximum
- An object of weight 120N vibrates with a period of 4.0s when hung from a spring. Calculate the force per unit length of the spring. [g= 10ms−2, π=3.142]
3. You are provided with a converging lens and holder, a screen, a ray box containing an illuminated object pin, and a meter rule.
- Place the lens in its holder such that it is facing a distant object seen through a well-lit laboratory window. Move the screen to and fro until a sharp image of the distant object is formed on it. Measure the distance, f00, between the screen and the lens.
- Clamp the meter rule securely to the table. Place the illuminated object pin at the end R of the meter rule.
- Place the lens at a position P such that X = RP =20cm.
- Move the screen to a position Q to receive a sharp image of the object. Measure the distance Y = PQ.
- Evaluate Z = (X+Y)
- Repeat the procedure for five other values of x = 25cm. 3Ocm, 35cm, 40cm and 45cm. In each case, record X,Y and evaluate Z.
- Tabulate the results.
- Plot a graph with Z on the vertical axis and X on the horizontal axis. Draw a smooth curve through the points.
- Determine from your graph the minimum value of Z=Z00 and its corresponding distance
- Evaluate W = ½ (Z04+X02Z04+X02)
- State two precautions taken to ensure accurate results.
- (b) i. Draw a ray diagram to show how a Convex lens forms an image of magnification less than one.
- Name two pairs of features in the human eye and a lens camera that performs similar functions.
4. You are provided with a battery of e.m.f. E, a key K, a voltmeter, a standard resistor R00= 2Ω, a resistance box R, and some connecting wires.
- Measure and record the e.m.f. E of the battery.
- Set up a circuit as shown in the diagram above with the key open.
- Set the resistance on the resistance box to R 22.
- Close the key, read and record the potential difference V on the voltmeter.
- Evaluate V−1−1
- Repeat the procedures for five other values of R = 5Ω 10Ω,12Ω,15Ω and 20Ω. In each case, record V and evaluate V−1
- Tabulate the results.
- Plot a graph with R on the vertical axis and V−1 l on the horizontal axis, starting both axes from the origin (0,0).
- Determine the slope, s, of the graph and the intercept c on the vertical axis.
- Calculate ∝and β from the equations s = R0 ∝ and c= – (R00+B).
- State two precautions taken to obtain accurate results.
