A How much kinetic energy will an electron gain in Joules if

(A) How much kinetic energy will an electron gain (in Joules) if it falls through a potential difference of 22.0 kV in a TV tube?

(B) An electric field of 686.0N/C is desired between two parallel plates 11.8 mm apart. What magnitude of potential difference needs to be applied across the plates?

(C) if the electric potential is constant in a region of space, what can you say about the electric field? Select one:

a. It must be the same constant

b. It must be decreasing

c. It must be zero

Solution

According to the given problems,

(A) The drop in potential energy is

U = q V = 1.602*10^-19C * 22.0*10³J/C = 3.52*10^-15 J

Thus P.E is converted into K.E of the electron, so the answer is 3.52*10^-15 J

(B)The potential difference needs to be applied across the plates

V = E*d = 686 * 11.8*10^-3 = 8.0948V

(C)As the eletric potensial is a constant, and the electric field shows the gradient of electric potential.

there\'s no electric field in the region of space,[C]