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 3 x 10⁸ m s^-1.

How is the frequency of a stretched string related to:

(i) it's length?

(ii) it's tension?

An electric bulb of resistance 500 Ω, draws a current of 0.4 A. Calculate the power of the bulb and the potential difference at it's end.

State two causes of energy loss in a transformer.