An electric field in a vacuum propagates at a speed of 300,000 km / s. How long does it take for it to spread
An electric field in a vacuum propagates at a speed of 300,000 km / s. How long does it take for it to spread over a distance equal to the radius of the Earth (on average R earth = 6.4 * 10 ^ 6) and to the distance from the Earth to the Sun (average distance to the sun R3-c = 1.5 * 10 ^ 11 m)?
Given:
v = 300000 km / s = 3 * 10 ^ 5 km / s – the speed of the electric field in vacuum;
R1 = 6.4 * 10 ^ 6 meters = 6.4 * 10 ^ 3 kilometers – the radius of the Earth;
R2 = 1.5 * 10 ^ 11 meters = 1.5 * 10 ^ 8 kilometers – the distance from the Earth to the Sun.
It is required to find the time t1 and t2 (seconds) during which the electric field will travel the distance R1 and R2.
t1 = R1 / v = 6.4 * 10 ^ 3/3 * 10 ^ 5 = 2.1 * 10 ^ -2 = 0.02 seconds.
t2 = R2 / v = 1.5 * 10 ^ 8/3 * 10 ^ 5 = 0.5 * 10 ^ 3 = 500 seconds.
Answer: the electric field will travel a distance equal to the Earth’s radius in 0.02 seconds, and the distance from the Earth to the Sun in 500 seconds (8.3 minutes).
