Question

When current flows through a conductor, then the order of drift velocity of electrons will be?
A. ${10^{10}}cm/s$
B. ${10^{ - 2}}cm/s$
C. ${10^4}cm/s$
D. ${10^{ - 1}}cm/s$

Answer 1

Hint: In this case, we will assume the ideal conditions to find the order of drift velocity of electrons. Also, we know that all the parameters in current electricity vary with each other (directly or indirectly) i.e., current, voltage, resistance, etc. Hence, analyze every aspect of the solution needed and then present it with a proper explanation in a scientific approach.

Formula used:
Drift Velocity of electrons can be calculated by using formula,
$v = \dfrac{I}{{nAQ}}$
Where, v = drift velocity of electrons in $m/s$
I = current flowing through the conductor
n = number of electrons
A = area of cross section of the conductor
Q = charge of an electron

Complete step by step solution:
As we all know, electrons move with different velocities in an arbitrary direction in absence of an electric field inside a conductor. But, whenever an electric current flows through a conductor, the electrons start moving towards positive potential with a certain velocity. The average velocity acquired by a charged particle in a conductor due to an electric field is called drift velocity.

Drift Velocity of electrons (or any charged particle) can be calculated by using formula
$v = \dfrac{I}{{nAQ}}$
By assuming ideal conditions such as $I = 1A$or $A = 1m/{s^2}$, the order of drift velocity of electrons can be calculated as ${10^{ - 4}}m/s$. This means, when current flows through a conductor, then the order of drift velocity of electrons will be ${10^{ - 4}}m/s$ i.e., ${10^{ - 2}}cm/s$.$(\therefore 1m = 100cm)$

Hence, the correct option is B.

Note: Since this is a partial-numerical-based problem hence, it is essential that the given question is to be analyzed very carefully to give an accurate solution. Also, as we assumed the ideal conditions to solve this question, we should know that the value of the drift velocity of electrons changes with the other values of current, cross-sectional area, etc., but the order will always remain the same.