High School Physics

Numericals on Drift Velocity class 12

Last updated on June 25th, 2023 at 02:30 pm

In this post, you will find solved Numericals on drift velocity for class 12. These numerical problems are based on the drift velocity of electrons and electric current.
( see the derivation of electric current and drift velocity equation )

Formulas Used

Electric Current I = nAve
Mean drift velocity v = I /[nAe]

where A = area of cross-section of the conductor, n = number of electrons per cubic meter, e = charge on each electron, and v = drift velocity of the electron.

Numericals on Drift Velocity for Class 12 [solved]

1 ] A copper wire has a cross sectional area of 7.85 x 10-7 m2. The number density of copper is 8.5 x 1028 m-3. Calculate the mean drift velocity of the electrons through the wire when the current is 1.4 A.


The equation to use: I = nAve ( see the derivation of the drift velocity equation )
=> mean drift velocity = v = I/(nAe)…. ……… (1)

As per the problem statement, A=7.85 x 10-7 m2
n=8.5 x 1028 m-3
and I = 1.4 A
We know, e=1.6 x 10-19

Putting all the values in equation 1, we will get:
v= 1.31 x 10-4 m/s

Drift velocity Numerical Extra Questions as exercise

Now solve the following numerical problems using the same formula.

Drift velocity Numericals class 12 - Extra Questions as exercise

Take Away | Suggested reading

Here we have solved numerical problems on the drift velocity of electrons and electric current.
You can go through the following related and suggested posts for a better understanding of the topic.

drift velocity and current – how slow drift velocity causes high-speed current

derive the relationship between drift velocity and current

See also  Seebeck effect
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