Magnitude of electric field in an area of changing magnetic field

[arnab321]

Homework Statement

A cylinder of radius R has a uniform, time varying mag. field B, (dB/dt < 0).
magnitude of electric field at a point P at a distance r (<R) is:

a) decreasing with r
b) increrasing with r
c) not varying with r
d) varying as r^-2

Homework Equations

The Attempt at a Solution

i think that electric field should be independent of r, as the field is uniform and doesn't vary with r, and the point is inside the cylinder.

 

[kushan]

hey arnab electric field is E=-d(phi)/dt
and phi depend on the area , and area depends on the radius :D

 

[arnab321]

hey arnab electric field is E=-d(phi)/dt
and phi depend on the area , and area depends on the radius :D

i think that's the Emf and not the electric field. anyways, option d is wrong (anyways, ur explanation wasnt even giving option d)

 

[kushan]

due Emf and Eds have a relation ?

 

[kushan]

sorry that was a typo

 

[arnab321]

electric field is (potential) x (dist.) but in this case what's the distance? why does it have to be the distance from centre?

 

[kushan]

refer NCERT man its all given there

 

[ehild]

The line integral of E around a closed curve is equal to the negative time derivative of the integral of B for the enclosed area.

$$\int{E_s ds}=-\int \frac{\partial B}{\partial t}dA$$The magnetic field is constant inside the cylinder, so the magnitude of the electric field is constant along a concentric circle by symmetry. Both E and B can be factored out from the integrals... ehild