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Im having problems with this question. Can someone help me? Demonstrate your kno

ID: 1762714 • Letter: I

Question

Im having problems with this question. Can someone help me?
Demonstrate your knowledge of how electric fields are related toelectric potentials. (a) What is the electric field E(r) = E(x, y,z) for the potential 2 2 2 V (x, y, z) = Ax + By Cz ?(Please remember that E is a vector with three components.) Thenevaluate E(r) at the point r = (2, 1, 3), with A = ½ , B = 2and C = 1. (b) What is the potential V(x) for an electric fieldEx(x) = E0 cos kx? Assume that Ey = Ez = 0, and that V0 =V(0) = E0 / k. Express your answer in terms of E0 and k. (Note thatthe quantity k here is not Coulomb’s constant, but is insteadthe wave number and has a value of
k=2/ with units of m1.)

Explanation / Answer

E = - del V = - 222 V ( A i + Bj + C k) =  -( 111 i + 444 j+ 222 k) V V(x) = - integral E dx = - E0 / k sin k x +C   where C = V(0) / k