The temperature at which the resistance of a conductor becomes 30% more than that of its resistance at 47°C will be: (Given the value of the temperature coefficient of resistance of the conductor is 2 × 10-4 K-1.)
1820 K
The resistance of a conductor varies with temperature according to the formula:
RT = R0(1 + αΔT)
Given that resistance increases by 30%, we set up:
1.3R0 = R0(1 + (2 × 10-4)ΔT)
Solving for ΔT:
1.3 = 1 + (2 × 10-4)ΔT
0.3 = (2 × 10-4)ΔT
ΔT = 1500 K
Final temperature = 47 + 1500 = 1820 K.
Thus, the correct answer is (b).
Important Questions from Current Electricity
The current through a 4/3 Ω external resistance connected to a parallel combination of two cells of 2 V and 1 V emf and internal resistances of 1 Ω and 2 Ω respectively is:
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A cell of emf 1.1 V and internal resistance 0.5 Ω is connected to a wire of resistance 0.5 Ω. Another cell of the same emf is now connected in series with the intention of increasing the current, but the current in the wire remains the same. The internal resistance of the second cell is:
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The magnetic moment of a thin bar magnet is 'M'. If it is bent into a semicircular form, its new magnetic moment will be:
