Question

1.In a television picture tube, electrons strike the screen after being accelerated from rest through a potential difference of 19000 V. The speeds of the electrons are quite large, and for accurate calculations of the speeds, the effects of special relativity must be taken into account. Ignoring such effects, find the electron speed just before the electron strikes the screen.

2.During a lightning flash, there exists a potential difference of V_cloud - V_ground = 1.0 x 10⁹ V between a cloud and the ground. As a result, a charge of -19 C is transferred from the ground to the cloud.

(a) How much work W_{ground–cloud} is done on the charge by the electric force?

(b) If the work done by the electric force were used to accelerate a 1100-kg automobile from rest, what would be its final speed?

(c) If the work done by the electric force were converted into heat, how many kilograms of water at 0 °C could be heated to 100 °C?

W_{ground–cloud} =

Answer 1