A steady current flows through the conductor of variable cross-sectional area. Now select the correct options.

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The value of current is same through the cross sections 1, 2 and 3

The current density is the maximum at the cross sections (3)

The drift velocity is greater at the cross section (1)

The electric filed is maximum at the cross section (3)

answer is A, B, D.

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Detailed Solution

All three cross-section are in series. So, the value of current is same through the cross sections 1, 2 and 3.

Current density, $J = \frac{i}{A}$

Cross sections (3) is smallest. So, the current density is the maximum at the cross sections (3).

Drift velocity, $v_{d} = \frac{i}{n e A} = \frac{J}{n e}$

Cross sections (3) is smallest. So, the current density is the maximum at the cross sections (3). Thus, the drift velocity is greatest at the cross section (3).

Electric Field, $E = ρ J$

Cross sections (3) is smallest. So, the current density is the maximum at the cross sections (3). Thus, the electric filed is maximum at the cross section (3).

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