Current Electricity 5 Question 17
17. A copper wire having cross-sectional area of and a length of is initially at and is thermally insulated from the surrounding. If a current of is set up in this wire, (a) find the time in which the wire will start melting. The change of resistance with the temperature of the wire may be neglected. (b) What will this time be, if the length of the wire is doubled?
(1979)
Melting point of copper
Show Answer
Solution:
- (a)
Substituting the values, we have
(b) From Eq. (i) we can see that time is independent of length of wire.