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A capacitor is connected across an ac generator whose frequency is 700 Hz and wh

ID: 1372979 • Letter: A

Question

A capacitor is connected across an ac generator whose frequency is 700 Hz and whose peak output voltage is 200 V. The rms current in the circuit is 2.8 A. (a) What is the capacitance of the capacitor? (b) What is the magnitude of the maximum charge on one plate of the capacitor? Note: The ac current and voltage are rms values and power is an average value unless indicated otherwise.

A capacitor is connected across an ac generator whose frequency is 700 Hz and whose peak output voltage is 200 V. The rms current in the circuit is 2.8 A. (a) What is the capacitance of the capacitor? (b) What is the magnitude of the maximum charge on one plate of the capacitor? Note: The ac current and voltage are rms values and power is an average value unless indicated otherwise.

Explanation / Answer

peak current in the circuit is

I = I_rms Sqrt ( 2)

= ( 2.8 A ) sqrt (2)

= 4 A

volatge across the capacitor is

V =I X_C

= I / 2 pi f C

C = I / 2 pi f V

= (4 A) / 2 pi (700 Hz ) (200 V )

= 4.54*10^ -6 C

= 4.54 micro C