For current entering at A, the electric field at a distance r from A is
Directions : Consider a block of conducting material of resistivity shown in the figure. Current I enters at A and leaves from D . We apply superposition principle to find voltage
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 in the block.
(ii) Calculate field E(r) at distance r from A by using Ohm’s law 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 I leaving D and superpose results for A and B
As we learnt in
If current density is uniform -
- wherein
Current density
Normal cross-section
Current density, '
Option 1)
This option is incorrect.
Option 2)
This option is incorrect.
Option 3)
This option is incorrect.
Option 4)
This option is correct.