LEDS that can emit red, yellow, orange, etc. commercially available.What are its advantages over ordinary bulbs?

LEDS that can emit red, yellow, orange, etc. commercially available.Write any two uses of LED.

LEDS that can emit red, yellow, orange, etc. commercially available.How these colours are obtained in a LED.

In Appollo space programme the fuel cells are used not only for electric power but also for prepare H_2 O for drinking. What do-you understand by a fuel cell? What are the advantages of fuel cells over ordinary cells?

If we show a red litmus paper over ammonia gas. What change can be observed?

A box contains 5 red and 10 black balls. A ball is drawn at random, its colour is noted and is returned to the box. More over 2 additional balls of the colour drawn are put in the box and then a ball is drawn.what is the probability that the second ball is red.

If we show a red litmus paper over ammonia gas, what change can be observed?

A radio can tune over the frequency range of a portion of MW broadcast: (800 KHZ to 1200 KHZ). If its LC circuit has an .effective inductance of 200 n H, what must be the range of its variable capacity?