At what speed do electrons move in a TV picture tube with an accelerating potential difference of 30 kW?

To calculate the speed of movement of electrons in the picture tube of the TV used, we use the equality: me * V2 / 2 = qe * (φ1 – φ2), whence V = √ (2 * qe * (φ1 – φ2) / me).

Values of variables and constants: qе – electron charge (qе = -1.6 * 10 ^ -19 C); φ1 – φ2 – accelerating potential difference (φ1 – φ2 = 30 kV = 30 * 10 ^ 3 V); me is the mass of an electron (me = 9.11 * 10 ^ -31 kg).

Calculation: V = √ (2 * qe * (φ1 – φ2) / me) = √ (2 * 1.6 * 10 ^ -19 * 30 * 10 ^ 3 / (9.11 * 10 ^ -31)) = 102654130 m / s ≈ 102.7 * 106 m / s.