(c) Alternating Current (AC) voltage can be easily increased or decreased
   (d) all the above
Ans: (d)
300. At temperature near O"K, (zero kelvin) metals such as lead and tin
   (a) insulators
   (b) semiconductors
   (c) superconductors
   (d) condenser
Ans: (c)
301. The overhead wires supported by high towers in the grid system carry
   (a) alternating current of very high frequency
   (b) alternating current of very high voltage
   (c) a very large direct current
   (d) a high voltage direct current
Ans: (b)
302. A radio set that uses valves does not start operating immediately when it
   is switched on whereas a set containing only tranaistors operates
   immediately. The reason for this is that
   (a) the valve filaments have low resistance
   (b) valve-radio sets work at a higher voltage
   (c) transistor set has a low resistance
   (d) filaments of the valves cake time to beat up and function
Ans: (d)
303. The body of an electrical appliance is earthed in order that
   (a) electricity may not leak
   (b) there may be smooth flow of electricity
   (c) a short circuit may be prevented
   (d) current may pass to the earth in case of a short circuit without doing any
       harm to the person
Ans: (d)
304. Air pressure is usually highest when the air is