Question

An electric kettle has 2 heating coils. When one of the coils is switched on

, the kettle begins to boil in’6’ min and when the other coil is switched on ,

the boiling begins in 8 min. In what time will the boiling begin if both the

coils are switched on simultaneously : a)in series b)in parallel

10. One metre long metallic wire is broken into two equal parts P and Q. The

part ‘P’ is uniformly extended into another wire R. Length of R is twice the

length of P and the resistance of R is equal to that of Q. Find the ratio of

the resistances of P and R and also the ratio of lengths of P and Q

Answer 1

b in a parallel because if you don't put them in a straight line they won't transfer heat to the coils