CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A steady current passes through a wire of non-uniform cross-section. The quantities which depend on the Area of cross-section are:

A
Free electron density
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
Resistivity
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
Drift velocity
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
Charge crossing in a given time interval
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is D Drift velocity
The drift velocity of electrons in a conductor is given by,
Vd =InAq
where, I is the current, n is the number of electrons, A is the area of cross section and q is the charge on charge carrier.
Steady current means a uniform current throughout the conductor. so current I is constant.
Thus, from this expression the Drift velocity increases inversely as area decreases.
So now the Drift velocity is inversely related to area A,
such that for larger areas of cross section, Vd is lower and for lower areas of cross section Vd is higher.
AVd is nearly constant such that current I remains same through any cross section of the wire.

The density of free electrons is number of free electrons per unit volume. which only depend upon material of the conductor, it's a constant value for same material because it is calculated over per unit volume.
So it is not affected by V or A. Hence Option A is wrong.

Resistivity of a material depends on the material alone and is independent of the length or cross section Area of the wire. Hence, option B is wrong.

Charge crossing in a given time interval is current I itself, which is given constant for any cross section in the wire. Hence option D is wrong.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Current Density Vector
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon