Current Electricity and Electrical InstrumentHard
Question
A wire of length L and 3 identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by ᐃT in a time t. A number N of similar cells is now connected in series with a wire of the same material and cross section but of length 2L. The temperature of the wire is raised by the same amount ᐃT in the same time. The value of N is
Options
A.4
B.6
C.8
D.9
Solution
In the first case 
t = ms ᐃT ......(i)
When length of the wire is doubled, resistance and mass both are doubled.
Therefore, in the second case
= (2m)s ᐃT .....(ii)
Dividing Eq. (ii) by (i), we get
2 or N2 = 36 or N = 6.
t = ms ᐃT ......(i)When length of the wire is doubled, resistance and mass both are doubled.
Therefore, in the second case
= (2m)s ᐃT .....(ii) Dividing Eq. (ii) by (i), we get
2 or N2 = 36 or N = 6.Create a free account to view solution
View Solution FreeTopic: Current Electricity and Electrical Instrument·Practice all Current Electricity and Electrical Instrument questions
More Current Electricity and Electrical Instrument Questions
In the circuit given below, V(t) is the sinusoidal voltage source, voltage drop VAB(t) across the resistance R is :-...A conducting square frame of side ′a′ and a long straight wire carrying current I are located in the same pl...A silver wire of length 10 metre and cross-sectional area 10-8 m2 is suspended vertically and a weight of 10 N is attach...In the arrangement shown in figure when the switch S2 is open, the galvanometer chows no deflection for . When the switc...n identical cells are joined in series with its two cells A and B in the loop with reversed polarities. EMF of each cell...