oldhw 32 - nguyen (jmn727) oldhomework 32 Turner (59070) 1...

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Unformatted text preview: nguyen (jmn727) oldhomework 32 Turner (59070) 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 6) 10.0 points You are designing a radio receiver based on the idea of a series LRC circuit as shown be- low. The two major radio stations in town are KUT and KMFA, which broadcast at frequen- cies 96 . 2 MHz and 95 . 2 MHz, respectively. Electromagnetic signals from these ra- dio stations simultaneously supply sinusoidal emf s E KUT = V sin( KUT t ) and E KMFA = V sin( KMFA t ) to the circuit via an antenna. The receiving circuit includes an inductor of 0 . 77 H, a variable capacitor C , and a speaker whose resistance you must choose. C R . 77 H V sin( t ) Speaker K U T K M F A At what value of the variable capacitance C will the sound volume ( i.e. , the power dissi- pated in the speaker) be maximum for KUT? Correct answer: 3 . 55467 pC. Explanation: Let : = 96 . 2 MHz , = 9 . 62 10 7 Hz , and L = 0 . 77 H , = 7 . 7 10 7 H . The frequency of KUT is KUT = 2 KUT = 2 (9 . 62 10 7 Hz) = 6 . 04442 10 8 Hz . At resonance KUT = 1 L C KUT , so C KUT = 1 L 2 KUT = 1 (7 . 7 10 7 H) (6 . 04442 10 8 Hz) 2 10 12 pC 1 C = 3 . 55467 pC . 002 (part 2 of 6) 10.0 points At what value of the variable capacitance C will the sound volume be maximum for KMFA? Correct answer: 3 . 62974 pC. Explanation: Let : KMFA = 95 . 2 MHz = 9 . 52 10 7 Hz The frequency of KMFA is KMFA = 2 KMFA = 2 (9 . 52 10 7 Hz) = 5 . 98159 10 8 Hz . Thus C KMFA = 1 L 2 KMFA = 1 (7 . 7 10 7 H) (5 . 98159 10 8 Hz) 2 10 12 pC 1 C = 3 . 62974 pC . 003 (part 3 of 6) 10.0 points In order for the radio receiver to be useful it must discriminate between the two radio stations. Your companys specifications state that when the radio is tuned to KUT, the...
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oldhw 32 - nguyen (jmn727) oldhomework 32 Turner (59070) 1...

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