A uniform but time varying magnetic field exists in cylindrical region and directed into the paper. If field decreases with time and a positive charge is placed at any point inside the region, then it moves :-

Options

A. along 1
B. along 2
C. along 3
D. along 4

Answer

D

Explanation

`int" E. dl"=-pi r^(2)("dB")/(dt)`
`E xx2pi r=+pi r^(2)xx("dB")/(dt)"as"("dB")/(dt)`

`=-"ve E"=+"ve"`
`:.` assume direction is right
so q charge move along 3