Question

An equilateral tringular loop `ADC` having some resistance is pulled with a constant velocity `v` out of a uniform magnetic field directed into the paper. At time `t=0`, side `DC` of the loop is at edge of the magnetic field.

A.
B.
C.
D.

Answer 1

Correct Answer - B
Let `2a` be the side of the triangle and `b` the length `AE`.
`(AH)/(AE)=(GH)/(EC)`
:. `GH=((AH)/(AE))EC` or `GH+((b-vt))/(b).a`
`=a-((a)/(b)vt)` :. `FG=2GH=2[a-(a)/(b)vt]`
Induced emf, `e=Bv(FG)=2Bv(a-(a)/(b)vt)`
:. Induced current `i=(e)/(R )=(2Bv)/(R )[a-(a)/(b)vt]`
or `i=k_(1)-k_(2)t`
Thus `i-t` graph is a straight line with negative slope and positive intercept.