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Class XII Physics Current Electricity 1
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Question 1
The total current supplied to the circuit by the battery is
Question 2
The resistance of bulb filament is 100 Ω at a temperature of 100 ºC. If its temperature coefficient of resistance be 0.005 per ºC, its resistance will become 200 Ω at a temperature of
Question 3
A material B has twice the specific resistance of A. A circular wire made of B has twice the diameter of a wire made of A. Then for the two wires to have the same resistance, the ratio lB/lA of their respective lengths must be
Question 4
A wire of resistor R is bent into a circular ring of radius r. Equivalent resistance between two points X and Y on its circumference, when angle XOY is 
can be given by
can be given by Question 5
The resistance of a wire is 5 ohm at 50 ºC and 6 ohm at 100 ºC. The resistance of the wire at 0 ºC will be
Question 6
If a wire is stretched to make it 0.1% longer, its resistance will
Question 7
Directions : Question is based on the following paragraph.
Consider a block of conducting material of resistivity ρ shown in the figure. Current I enters at A and leaves from D. We apply superposition principal to find voltage ΔV developed between B and C. The calculation is done in the following steps :
(i) Take current I entering from A and assume it to spread over a hemispherical surface on the block.
(ii) Calculate field E(r) at distance r from A by using Ohm’s law E =ρj, where j is the current per unit area at r.
(iii) From the r dependence of E(r), obtain the potential V(r) at r.
(iv) Repeat (i), (ii) and (iii) for current T leaving D and superpose results for A and D.
For current entering at A, the electric field at a distance r from A is
Consider a block of conducting material of resistivity ρ shown in the figure. Current I enters at A and leaves from D. We apply superposition principal to find voltage ΔV developed between B and C. The calculation is done in the following steps :
(i) Take current I entering from A and assume it to spread over a hemispherical surface on the block.
(ii) Calculate field E(r) at distance r from A by using Ohm’s law E =ρj, where j is the current per unit area at r.
(iii) From the r dependence of E(r), obtain the potential V(r) at r.
(iv) Repeat (i), (ii) and (iii) for current T leaving D and superpose results for A and D.
For current entering at A, the electric field at a distance r from A is
Question 8
The space between two concentric metallic spheres of radii R1 and R2 is filled with a material of conductivity σ. The total resistance of the system is –
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Jul 31JEE & BITSAT
