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Physics · 2023 · 3 marks
CBSE 2023 · Region 3 · Set 1 · Q26
A potential difference V is applied across a conductor of length l and uniform cross-section area A. How will the (i) electric field E, (ii) drift…
A potential difference V is applied across a conductor of length $\displaystyle l$ and uniform cross-section area A . How will the (i) electric field E , (ii) drift velocity $\displaystyle \mathrm{v}_{\mathrm{d}}$, and (iii) current density j be affected when (a) V is doubled and (b) $\displaystyle l$ is halved (keeping other factors constant)?
Marking-scheme solution
(a) When V is doubled,
(i) Electric field is doubled.
(ii) Drift velocity is doubled.
(iii) Current density is doubled
(b) When \(\displaystyle l\) is halved,
(i) Electric field is doubled.
(ii) Drift velocity is doubled.
(iii) Current density is doubled
Alternatively:(i) \(\displaystyle E=\frac{V}{l} ; \quad \therefore E^{\prime}=2 E\)
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