# Dependence like the e field finally to distinguish

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) dependence like the E -field. Finally, to distinguish between vector B = + E 0 c cos( k y ω t ) and vector B = E 0 c cos( k y ω t ) , the Poynting vector S = E × B must point in the direc- tion of propagation. Thus, for example, at the point y = 0, B must point in the + x direction, which, at t = 0, corresponds to B = + E 0 c cos( k y ω t ). 012(part1of3)10.0points A point light source S produces radiative power P = 56 . 1 W . It radiates light isotrop- ically. A mirror is placed at point B , which is a distance 1 . 88 m away from the source S . Find the total force on the mirror. Determine the light intensity I at point X . 3. I = P 2 π r 2 4. I = P 4 π r 2 correct 5. I = π r 2 P 6. I = P π r 2 7. I = 4 π r 2 P 8. I = P π 4 r 2 Explanation: BasicConcepts: Intensity: I = P A Pressure: p = F A The point light source radiates in all di- rections, so the power is spread out on the surface of a sphere I = P A = P 4 π r 2 = 1 . 2631 W / m 2 . 013(part2of3)10.0points Find the total force on the mirror.
liang (xl5432) – HW11 – niu – (57625) 5 leading to a force F = p A = (8 . 42649 × 10 9 N / m 2 ) (0 . 000232 m 2 ) = 1 . 95495 × 10 12 N , on the mirror. 014(part3of3)10.0points Calculate the maximum electric field of the oscillatory electromagnetic wave at X . 015(part1of3)10.0points A plane electromagnetic wave is generated due to the initiation of current along the y direction in a current sheet in the xy plane at z = 0. A steady flow current is switched on at t = 0. This current sheet generates a traveling “front” of the electric and magnetic fields. z x y infinite current sheet in x, y plane
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