An electron at point `A` in figure has a speed `v_0 = 1.41 xx 10^6 m/s`. Find

(a) the magnitude and direction of the magnetic field that will cause the electron to follow the semicircular path from `A` to `B`,
(b) the time required for the electron to move from `A` to `B`.

Answer

A

Explanation

a. At `A`, magnetic force should be towards right.
From Fleming's left hand rule, magnetic field should be inwards.
Further `r=(mv)/(Bq)`
`:. B=(mv)/(qr)` `(r=5cm)`
b. `t_(AB)=T/2=(pim)/(Bq)`