Question

Two plates separated by a distance 16.3 mm are charged to a potential difference of 7.25 volts. A constant 6 81 N force pushes a -8.30 mC charge from the positively charged plate to the negatively charged plate. Using the concept of work-energy. Calculate the change In When energy deltaT. potential energy and total energy deltaE of the charge as it travels from one plate to the other Assume the initial speed of the electron is 0.

Answer 1

Change in Potential = q deltaV

and deltaV = - 7.25 volts

deltaU = -8.30 x 10^-3 x -7.25 = 60.175 x 10^-3 J    ......Ans

Its potential energy increase.

And

Work done by force = F.d = 6.81 ( 16.3 x 10^-3 m) = 111 x 10^-3 J

Using work energy theorem,

Work done by force + work done by electric force = change in KE

(work done = - deltaU)

111 x 10^-3 + ( - 60.175 x 10^-3) = deltaKE

deltaKE Or deltaT = 50.83 J .......Ans

total enery change, deltaE = T + U = 111 x 10^-3 J .....Ans