CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

A metallic rod of length l is tied to a string of length 2l and made to rotate with angular speed ω on a horizontal table with one end of the string fixed. If there is a vertical magnetic field B in the region, the e.m.f. induced across the ends of the rod is


A
2Bωl32
loader
B
3Bωl32
loader
C
4Bωl22
loader
D
5Bωl22
loader

Solution

The correct option is D 5Bωl22
Let us try to solve it  by dimensional analysis first rather than going for conventional approach.
We know that the emf induced in a rod rotating with angular velocity ω in a region of magnetic field is given by
Emf = Bωl2
Now, if we see options (a) and (b) are not dimensionally correct so they must be omitted.

Option (c) can be written as 2Bωl2 
2Bωl2=B(2ωl)l = B(ω×2l)l
But this would be the emf across metallic string and not across the metallic rod. Emf across the rod needs to be more than 2Bωl2 because length increases further after string.
So,  option (d) is the correct answer. 
 

Physics

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image