What is the SI unit of energy? How is the electron volt (eV) related to it? 

State the energy changes that takes place in the following when they are in use:

i) a photovoltaic cell

ii) an electromagnet

A body of mass 5 kg is moving with a velocity of 10 m/s. What will be the ratio of its initial kinetic energy and final kinetic energy, if the mass of the body is doubled and its velocity is halved? 

6.5 kJ of energy causes a displacement of 64 m in a body in the direction of force in 2.5 seconds. Calculate:

i) the force applied

ii) power in horse power(hp)

[ Take 1 hp = 764 W]

With reference to the terms mechanical advantage, velocity ratio and efficiency of a machine, name the term that will not change for a machine of a given design.

ii) Define the term stated by you in part (i). 

A ray of light strikes the surface of a rectangular glass block such that the angle of incidence is i) 0^o ii) 42⁰. Sketch a diagram to show the approximate the path taken by the ray in each case as it passes through the glass block and emerges from it. 

State the conditions required for total internal reflection of light to take place.

Copy and complete the following table:

i) Copy and complete the diagram to show the formation of the image of the object AB.

ii) What is the name given to X. 

i) Why is white light considered to be polychromatic in nature?