Question

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What does principal focus mean?​

Answer 1

Answer:

The electric field E is defined to be E=Fq E = F q , where F is the Coulomb or electrostatic force exerted on a small positive test charge q. E has units of N/C. The magnitude of the electric field E created by a point charge Q is E=k|Q|r2 E = k | Q | r 2 , where r is the distance from Q.The maximum value of E in an electromagnetic wave propagating in X-direction is 1000 Newton/coulomb which is in Z direction.