A 1 µA beam of protons with a cross-sectional area of 0.5 sq. mm is moving with a velocity of 3 x 104 ms-1. Then charge density of beam is
6.6 x 10-4 C / m3
6.6 x 10-5 C / m3
6.6 x 10-6 C / m3
None of these
For one second, distance = Velocity = 3×10−4m/sec
and Q=i×1=10−6C. Charge density=ChargeVolume10−63×104×0.5×10−6=6.6×10−5C/m3.