A `1 mu A` beam of protons with a cross - sectional area of `0.5 sq.mm` is moving with a velocity of `3 xx 10^(4) ms^(-1)` . Then charge density of beam is

Options

A. `6.6 xx 10^(-4) C//m^(3)`
B. `6.6 xx 10^(-5) C//m^(3)`
C. `6.6 xx 10^(-6) C//m^(3)`
D. None of these

Answer

B

Explanation

For one second , distance ` = velocity = 3 xx 10 ^(-4) m// sec`
and `Q = i xx 1 = 10^(-6) C`. "Charge density" `= ( "Charge")/("Volume")`
`(10^(-6))/(3 xx 10^(4) xx 0.5 xx 10^(-6)) = 6.6 xx 10^(-5) C//m^(3)`.