The anode positive terminal of an Xray tube is at a potentia

The anode (positive terminal) of an X-ray tube is at a potential of 120,000 V with respect to the cathode (negative terminal). How much work (in Joules) is done by the electric force when an electron is accelerated from the anode to the cathode? If the electron is initially at rest, find the speed of the electron when it arrives at the cathode. (e = 1.6 * 10^-19 C, me =9.1 * 10^-31 kg)

Solution

a) Energy is just Charge*voltage so in this case it\'s easy.

W = eV = e(120,000V) = 120,000 * 1.6 * 10^-19V = 1.92*10^-14 joule

b) By conservation of energy,

K = W = 120000eV