A. 180″

**B. 90°**

C. 60°

D. 0°

# A.C. Fundamentals, Circuits and Circuit Theory

## In series resonant circuit, increasing inductance to its twice value and reducing capacitance to its half value__________?

A. will change the maximum value of current at resonance

B. will change the resonance frequency

C. will change the impedance at resonance frequency

**D. will increase the selectivity of the circuit**

## At very low frequencies a series R-C circuit behaves as almost purely___________?

A. resistive

B. inductive

**C. capacitive**

D. none of the above

## The r.m.s. value of alternating current is given by steady (D.C.) current which when flowing through a given circuit for a given time produces__________?

A. the more heat than produced by A.C. when flowing through the same circuit

**B. the same heat as produced by A.C. when flowing through the same circuit**

C. the less heat than produced by A.C. flowing through the same circuit

D. none of the above

## Time constant of an inductive circuit_________?

**A. increases with increase of inductance and decrease of resistance**

B. increases with the increase of inductance and the increase of resistance

C. increases with the decrease of inductance and decrease of resistance

D. increases with decrease of inductance and increase of resistance

## The safest value of current the human body can carry for more than 3 second is_________?

A. 4 mA

**B. 9 mA**

C. 15 mA

D. 25 mA

## In an A.C. circuit power is dissipated in____________?

**A. resistance only**

B. inductance only

C. capacitance only

D. none of the above

## The phase difference between voltage and current wave through a circuit element is given as 30°. The essential condition is that

**A. both waves must have same frequency**

B. both waves must have identical peak values

C. both waves must have zero value at the same time

D. none of the above

## The frequency of an alternating current is____________?

A. the speed with which the alternator runs

B. the number of cycles generated in one minute

**C. the number of waves passing through a point in one second**

D. the number of electrons passing through a point in one second

## In any A.C. circuit always__________?

**A. apparent power is more than actual power**

B. reactive power is more than apparent power

C. actual power is more than reactive power

D. reactive power is more than actual power