An electron in a TV CRT moves with a speed of 6.10 ✕ 107 m/s, in a direction perpendicular to the Earth's field, which has a strength of 5.00 ✕ 10−5 T. (a) What strength electric field (in kV/m) must be applied perpendicular to the Earth's field to make the electron move in a straight line?

The strength of the electric field is 3.05 kV/m

Explanation:

Given;

speed of electron, v = 6.10 ✕ 10⁷ m/s

strength of magnetic field, B = 5.00 ✕ 10⁻⁵ T

Electric force on the electron, F = Eq

Magnetic force on the electron, F = qvB

Eq =  qvB

E = vB

Where;

E is the electric field strength

v is the velocity of the electron

B is the magnetic field strength

E = vB = 6.10 x 10⁷ x 5.00 x 10⁻⁵

E = 3050 V/m = 3.05 kV/m

Therefore, the strength of the electric field is 3.05 kV/m

this would be about 43%