In a photocell

PHYSICS · Subjective · CBSE · Physics · Moving Charges and Magnetism · Moving Charges and Magnetism

Problem

In a photocell, plates

P

and

Q

are separated by

5\ \text{cm}

and connected through a galvanometer without any cell. Bichromatic light of wavelengths

4000\ \text{\AA}

and

6000\ \text{\AA}

is incident on plate

Q

, whose work function is

2.39\ \text{eV}

. If a uniform magnetic field

B

exists parallel to the plates, find the minimum value of

B

for which the galvanometer shows zero deflection.