The diagram below illustrates a structure of a typical photocell.

(i) Identify each of the parts labelled A and B.

(ii) State one function each of A and B

(iii) Einstein’s photoelectric equation can be written as E = hf – Wo. State what each of the terms E, hf and Wo represent.

(b) A photon is incident on a metal whose work function is 1.32 eV. An electron is emitted from the surface with a maximum kinetic energy of 1.97 eV. Calculate the frequency of the photon. [1 eV = 1.6 x 10-19 J]

(c)(i) Define half-life of a radioactive element.

(ii) Sketch a graph of the relation N = Noe-λt and indicate the half-life.

A well-lagged bar of length 100cm has its ends maintained at 100^oC and 40^oC respectively. What is the temperature at a point 60cm from the hotter end?

• A. 58^oC
• B. 62^oC
• C. 64^oC
• D. 76^oC

If a container is filled with ice to the brim, what happens to the level of water when the ice completely melts?

• A) the level of water goes up
• B) the water in the glass outflows
• C) the level of water remains unchanged
• D) the level of water drops

A household refrigerator consumes electrical energy at the rate of 200 W. lf electricity costs 5 k per kWh, calculate the cost of operating the appliance for 30 days.

• A. N7.20
• B. N12.00
• C. N30.00
• D. N33.33

The image of a pin formed by a diverging lens of focal length 10cm is 5cm from the lens. Calculate the distance of the pin from the lens

• A. -3.3cm
• B. 3.3cm
• C. 10.0cm
• D. 15.0cm

A metal rod of length 50cm is heated from 40^oC to 80^oC. If the linear expansivity of the material is \(\alpha\), calculate the increase in length of the rod (in metres) in terms of \(\alpha\)

• A. 20\(\alpha\)
• B. 200\(\alpha\)
• C. 2000\(\alpha\)
• D. 20000\(\alpha\)

When very hot water is poured into two identical thin and thick glass tumblers in equal volumes, the thick one cracks because?

• A. of the even expansion of glass
• B. glass is a crystal
• C. glass is a good conductor of heat
• D. of the uneven expansion of gass

A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary windings if the secondary has 25 turns?

• A. 20
• B. 250
• C. 200
• D. 500

A quantity of water at 20^oC is mixed with another quantity of water at 70^oC. The final steady temperature of the mixture is 40^oC. Determine the ratio of the mass of the cold water to that of the hot water

• A. 7:2
• B. 3:2
• C. 2:5
• D. 1:2

Lenz’s law of electromagnetic induction is essentially a statement of the

• A. Inverse square law of gravitation
• B. Inverse square law of magnetism
• C. Inverse square law of electrostatics
• D. Law of conservation of energy