What is the cost of running five 50W lamps and four 100W lamps for 10 hours if electrical energy costs 2 Kobo per KWh?

• A. N0.65
• B. N0.39
• C. N3.90
• D. N0.13

Which of the following is a property of steel?

• A) it cannot retain its magnetism longer than iron
• B) it can be used for making temporary magnets
• C) it can be used for making permanent magnets
• D) it can easily be magnetized and demagnetized

In which of the following diagrams is the length of the tube equal to one wavelength?

• A. A
• B. B
• C. C.
• D. D

A ball of mass 5.0kg hits a smooth vertical wall normally with a speed of 2ms^-1 and rebounds with the same speed. Determine the impulse experienced by the ball

• A. 20.0kg ms^-1
• B. 10.0kg ms^-1
• C. 5.0kg ms^-1
• D. 1.3kg ms^-1

A bar magnet is placed near and lying along the axis of a solenoid connected to a galvanometer. The pointer of the galvanometer shows no deflection when

• A. the magnet is moved away from the stationary solenoid
• B. the solenoid is moved away from the stationary magnet
• C. the magnet is moved towards the stationary solenoid
• D. there is no relative motion between the magnet and the solenoid

When the linear momentum of a body is constant, the net force acting on it

• A. is zero
• B. increases
• C. decreases
• D. remains constant

(a) Explain the term photoelectric effect.

(b)

The diagram below represents a photocell with its associated electric circuit. Identify each of the physical quantities

represented by the letters A, B, C, D, E and F

(c) What factor determines the: (i) current produced by the photocell

(ii) maximum kinetic energy of the photoelectrons?

(d) State one similarity and one difference between photoemission and evaporation

(e) Name two methods by which a beam of free electrons may be produced other than photoemission

(f) State two applications of photoelectric effect.

(g) A light wavelength 5.0 x 10\(^{-7}\) m is incident on metal resulting in photoemission of electrons. If the work function of the metal is 3.04 x 10\(^{-19}\)J, calculate the:

(i) frequency of the light

(ii) energy of the incident photon,

(iii) maximum kinetic energy of the photoelectrons (Speed of light = 3.00 x 108ms\(^{-1}\); Planck's constant = 6.6 x 10\(^{-34}\)Js).

(a) On which day would sound wave travel faster: on a hot or cold day? Explain.

(b) Why are megaphones shaped like funnels?

(c) A ray of light is incident on a surface of a ectangular glass prism of refractive index 1.5 illustrated in the diagram below.

(i) Copy the diagram a label the angles of: (\(\alpha\)) Incidence (x); (\(\beta\)) Reflection (y); (\(\gamma\)) refraction (z); with t glass letters indicated.

(ii) Calculate the angle refraction to the nearest whole number.

(d) A sonomesr wire vibrates in simple harmoi motion with a maximum amplitude of 1.0 cm. Calculate the frequency of vibration of the wire, giv that the magnitade of the maximum acceleration of the wire is 980ms\(^{-2}\). [\(\pi = \frac{22}{7}\)]

A man wears convex lens glasses of focal length 30cm in order to correct his eye defect. instead of the optimum 25cm, his least distance of distinct vision is

• A. 14cm
• B. 28cm
• C. 75cm
• D. 150cm

Which of the following statements is not correct?

• A. The pitch of a note depends on the frequency of the vibrating source
• B. The loudness of a note depends on its intensity
• C. The velocity of sound in air does not depend on the intensity of the note producing it
• D. Wind speed effects on the speed of sound in air