InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
(A) Consider circuit How much energy is absorted by electrons from the initial state of no current to the state of draft velocity? (b) Electrons give up energy at the rate of `Rt^(2)` per second in the thermal energy What time state would one assoclate energy with energy in problem (a) ? n = no of electron /volume `= 10^(29)//m^(3)` length of ciruit `= 10 cm` cross section `A = (1 mm)^(2)` |
|
Answer» (a) current `I = (V)/(R) = (6V)/(6 Omega) = 1A`, driff velocity `v_(d) = (I)/(nA e) = (1)/(10^(29) xx (10^(-4)) xx (1.6 xx 10^(-19)) = (1)/(1.6) xx 10^(-4) m//s` No of electron in the wire `= nAI` KE of all the electron `= (1)/(2) m_(e) u_(d)^(2) xx nAI = (1)/(2) xx (9.1 xx 10^(-31)) xx ((1)/(16) xx 10^(-4))^(2) xx 10^(29) xx(10^(-4)) xx 10^(-1)` `= 2 xx 10^(-17) J` (b) power loss `= I^(2) xx 6 = 6 J//s` All the `KE` of electron would be lost in time `= (2 xx 10^(-17)J)/(6 J//s) = 0.33 xx10^(-17) s ~~ 10^(-17) s` |
|