JEE MAIN - Physics (2021 - 17th March Morning Shift - No. 16)
A current of 10A exists in a wire of cross-sectional area of 5 mm2 with a drift velocity of 2 $$\times$$ 10$$-$$3 ms$$-$$1. The number of free electrons in each cubic meter of the wire is ___________.
625 $$\times$$ 1025
1 $$\times$$ 1023
2 $$\times$$ 1025
2 $$\times$$ 106
Explanation
$$I = neA{V_d}$$
$$n = {I \over {eA{V_d}}}$$
$$ = {{10} \over {1.6 \times {{10}^{ - 9}} \times 5 \times {{10}^{ - 6}} \times 2 \times {{10}^{ - 3}}}}$$
$$ = {{{{10}^{25}}} \over {16}} = 6.25 \times {10^{27}} = 625 \times {10^{25}}$$
$$n = {I \over {eA{V_d}}}$$
$$ = {{10} \over {1.6 \times {{10}^{ - 9}} \times 5 \times {{10}^{ - 6}} \times 2 \times {{10}^{ - 3}}}}$$
$$ = {{{{10}^{25}}} \over {16}} = 6.25 \times {10^{27}} = 625 \times {10^{25}}$$
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