Entry Test MCQ :: Alternating Current

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11.

If capacitance of L-C circuit is made four times then frequency of the circuit becomes

A.	Twice	B.	One half
C.	Four times	D.	None

12.

A capacitor of capacitance 30?F is charged by a constant current of 10mA. If initially the capacitor was uncharged what is the time taken for the potential difference across the capacitor to reach 300V?

A.	0.9sec	B.	15 sec
C.	1.5x105sec	D.	0.9x102sec

13.

The value of the steady current which when flowing through the same resistor produces heat at the same rate as the mean rate of heat produced by the alternating current is

A.	Average current	B.	Sinusoidal current
C.	r.m.s current	D.	Net current

14.

To find the r.m.s value of an alternating current mathematically we need to have

A.	Mean value of I2	B.	Square root of mean value of I2
C.	Square root of I2	D.	Square of 1/2

15.

An alternating current of r.m.s value of 4.0 A and frequency 50Hz flows in a circuit containing 10? resistor. The peak current is then

A.	20A	B.	20.66A
C.	6.66A	D.	5.66A

16.

An alternating current of r.m.s value of 2A and a steady direct current I flowing through identical resistors dissipate heat at the same rate. What is the current I?

17.

An alternating current is represented by the equation I = I?sin?t which of the following equation represents an alternating current of frequency and amplitude twice that of the above current?

A.	I = 2I?Sin(?t/2)	B.	I = 2I?Sin(2?t)
C.	I = 2ISin?t	D.	I = I?sin(2?t)

18.

pure resistor circuit the voltage and current are

A.	Lagging each other	B.	They are at 90? phase difference
C.	They have zero phase difference	D.	No phase difference

19.

When A.C current passes through a capacitor then the current relation will be

20.

In capacitive circuit the current

A.	Lags behind voltage by ?/2	B.	Is in phase with voltage
C.	Opposite in phase of voltage by ?	D.	Leads forward the voltage by ?/2