Question

In vacuum tube ,3×10power6 electrons per second strike anode plate kept at 480v. Find the rate of heat generation at the plate.

Answer 1

In vacuum tube , 3 × 10^6 electrons per second strike anode plate kept at 480v.

we know, charge on each electron, e = 1.6 × 10^-19 C

so, charge on 3 × 10^6 electrons = 3 × 10^6 × 1.6 × 10^-19 C

= 4.8 × 10^-13 C

hence, 4.8 × 10^-13 C charges flows through plate per second .

in time t, total charges flow through plate , Q = 4.8 × 10^-13t C

now given, potential difference, V = 480 volts.

so, Heat, H = potential difference × total charges

H = 480 × 4.8 × 10^-13t

H = (4.8)² × 10^-11t

or, H/t = 23.04 × 10^-11 J/s

hence, rate of heat generation at the plate = 23.04 × 10^-11 J/s