# hw17a - aldawsari(ma28683 – HW17 – Betancourt –(16856...

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Unformatted text preview: aldawsari (ma28683) – HW17 – Betancourt – (16856) 1 This print-out should have 9 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 32.1-32.6 001 10.0 points In a particular medium the speed of light is six-sevenths that of the speed of light in vacuum and the electric field amplitude has a maximum value of 7 . 4 mV / m. The speed of light is 2 . 99792 × 10 8 m / s . Calculate the maximum value of the mag- netic field. Correct answer: 2 . 87977 × 10- 11 T. Explanation: Let : E = 7 . 4 mV / m and c = 2 . 99792 × 10 8 m / s . The index of refraction is n ≡ c v , so the index of refraction of light in this particular medium is seven-sixths. According to Maxwell’s laws, for an elec- tromagnetic wave, the relation between the amplitude of the electric field and the magni- tude of the magnetic field is given by E = c n B = v B , where n is the index of refraction and v is the velocity of light in that medium. For our problem n = 7 6 since v = 6 7 c , so the maximum value of the magnetic field is B = 7 6 E c = 7 6 7 . 4 mV / m 2 . 99792 × 10 8 m / s · V 10 3 mV = 2 . 87977 × 10- 11 T . 002 (part 1 of 2) 10.0 points The cable is carrying the current I ( t ). Evaluate the electromagnetic energy flux S at the surface of a long transmission cable of resistivity ρ , length ℓ and radius a , using the expression vector S = 1 μ vector E × vector B . 1. S = μ ǫ ρ I 2 π a 2 2. S = ǫ μ I 2 2 π a 2 3. S = ρ ℓ I 2 π a 2 4. S = μ I 2 2 π a 2 5. S = π a 2 I 2 ρ ℓ 6. S = ρ I 2 2 π 2 a 3 correct 7. S = I 2 4 π μ c ℓ 8. None of these....
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hw17a - aldawsari(ma28683 – HW17 – Betancourt –(16856...

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