Electrons give up energy at the rate of `Rl^(2)` per second to the thermal energy. What time scale would number associate with energy in problem (a) ? N = no of electron/ volume = `10^(29)//m^(3)` , length of circuit = 10 cm , cross-section = A = `(1 mm )^(2)`

Explanation

Power dissipated,
P = `I^(2) ` R
`(E)/(l) = (1)^(2) xx 6 `
`therefore (E)/(t) = 6 W`
`therefore t = (E)/(6) = (2xx 10^(-17))/(6) " " [ because "K.E." = E]`
`therefore t = (1)/(3) xx 10^(-17)`
`therefore t approx 0.33 xx 10^(-17) ` s
`therefore t approx 3.3 xx 10^(-18) ` S