Q)
Consider a block of conducting material of resistivity ‘p’ shown in the figure. Current ‘I’ enters at ‘A’ and leaves from ‘D’. We apply superposition principle to find voltage ‘$\triangle$V’ developed between ‘B’ and ‘C’. The calculation is done in the following steps:<br>
(i) Take current ‘I’ entering from ‘A’ and assume it to spread over a hemispherical surface in the block<br>
(ii) Calculate field E(r) at distance ‘r’ from A by using Ohm’s law E = pj, where j is the current per unit area at ‘r<br>
(iii) From the ‘r’ dependence of E(r), obtain the potential V(r) at r.<br>
(iv) Repeat (i), (ii) and (iii) for current ‘I’ leaving ‘D’ and superpose results for ‘A’ and ‘D’.<br>
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QUESTION : $\triangle$V measured between B and C is
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