Question

We are able to obtain fairly currents in a conductor because
A. The electron's drift speed is usually very large.
B. The number density of free electrons is very high and this can compensate for the low values of the electrons drift speed and the very small magnitude of the electrons charge.
C. The number density of free electrons as well as the electrons drift speeds are very large and these compensate for the very small magnitude of the electrons charge.
D. The very small magnitude of the electron's charge has to be divided by the still smaller product of the number density and the drift speed to get the electric current.

Answer 1

Hint: First we need to find the relation between the current flows through the conductor, number of free electrons, charge of the electrons and the drift velocity of the electrons flowing through the conductor. Then only we can tell on what quantities the current flowing through the conductor depends on.

Formula used:
Current flowing through the given wire;
$I = neA{v_d}$
Where, n is no. of free electrons.
A is the area of the cross-section of the conductor given.
${v_d}$ is the drift velocity of electrons flowing through the given wire.
And e is the charge of the electron flowing in the wire.

Complete step by step solution:
From the formula of current, we know that;
$I = neA{v_d}$
So, the value of current, I depend on:
- The number of free electrons,
- Area of cross-section of the given conductor,
- Drift velocity of the electrons flowing,
- And the charge of the electron.

In the case of conductors: we know that the number density of the free electrons is very high. So if all the other quantity values are low then also we can obtain fair current in case of conductor. If the value of electron drift velocity is low and also the very small value of the charge of the electron then also the high value of number density free electrons can compensate for that.

Hence, the correct answer is option B.

Note: If in place of the conductor, a semiconductor will be there then it will be tough to find the fair current as there are less number density of free electrons in the semiconductor as compared to the conductor. Hence, the material used does matter and the answer depends on it.