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ID: 2119807 • Letter: #
Question
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The primary of a step-down transformer has 170 turns and is connected to a 120 V rms line. The secondary is to supply 27 A at 6 V.
(a) Find the current in the primary.
? A
(b) Find the number of turns in the secondary, assuming 100% efficiency.
? turns
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(a) How much energy is stored in the system?
? J
(b) What is the frequency of oscillation of the circuit?
? Hz
(c) What is the maximum current in the circuit?
? A
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A resistance R and a 1.5-H inductance are in series across a 60-Hz ac voltage. The voltage across the resistor is 32 V and the voltage across the inductor is 20 V. Assume that all voltages in this problem are rms voltages.
(a) What is the resistance R?
? ohm
(b) What is the ac input voltage?
? V
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Explanation / Answer
FIRST ANSWER: capacitive reactance Xc and inductive reactance XL Xc= 1/(wc) and XL = wL. Xc = XL at w=1/(sqrt(LC)). Insert the values to get w = 0.9535 *10^4 = 09535 SECOND ANSWER: Xc is given as 1000 ohm. w= 1/(1000C) substituting C, w = 666.67.
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