Draw a ray diagram to show the refraction of a monochromatic ray through a prism when it suffers minimum deviation.

The human ear can detect continuous sounds in the frequency range from 20 Hz to 20,000 Hz. Assuming that the speed of sound in air is 330 ms-1 for all frequencies; calculate the wavelengths corresponding to the given extreme frequencies of the audible range.

An enemy plane is at a distance of 300 km from a radar. In how much time the radar will be able to detect the plane? Take velocity of radio waves as x 10⁸ ms^-1.

How is the frequency of a stretched string related to:
(i) it’s length
(ii) it’s tension?

Define specific resistance and state its SI unit.

An electric bulb of 300 Ω draws a current of 0.4 A. Calculate the power of the bulb and the potential difference at its ends.

State two causes of energy loss in a transformer.

State two characteristics of a good thermion emitter.

State two factors upon which the rate of emission of thermions depends?

20.

When does the nucleus of an atom tend to be radioactive?