A series resonant LCR circuit has a quality factor ( Q-factor) 0.4. If  R = 2 kΩ,  C = 0.1 μF, then the value of inductance is

• 0.1 H

• 0.064 H

• 2 H

• 5 H

Assertion:  At resonance, LCR series circuit have a minimum current. 

Reason:  At resonance, in LCR series circuit, the current  and  e.m.f are not in phase with each other.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

143.

An inductive circuit contains a resistance of 10 Ω and an inductance of 2 H, If an AC voltage of 120 V and frequency 60 Hz is applied to this circuit, the current would be nearly

• 0.72 A

• 0.16 A

• 0.48 A

• 0.80 A

In an oscillating system, a restoring force is a must. In an L-C circuit, restoring force is provide by

• capacitor

• inductance

• resistance

• both (a) and (b)

In an AC circuit, voltage V = V₀sinωt  and inductor L is connected across the circuit. Then the instantaneous power will be

• $\frac{{\mathrm{V}}_0^2}{2\mathrm{\omega L}} \mathrm{sin\omega t}$

• $\frac{- {\mathrm{V}}_0^2}{2\mathrm{\omega L}} \mathrm{sin\omega t}$

• $\frac{- {\mathrm{V}}_0^2}{2\mathrm{\omega L}} \sin 2\mathrm{\omega t}$

• $\frac{{\mathrm{V}}_0^2}{\mathrm{\omega L}}\sin 2\mathrm{\omega t}$

Two sinusoidal waves of intensity I having same frequency and same amplitude interferes constructively at a point. The resultant intensity at a point will be

• I

• 2I

• 4I

• 8I

In given series LCR circuit R = 4Ω, X_L = 5 Ω and X_C = 8Ω, the current

• Leads the voltage by tan^-1(3/4).

• Leads the voltage by tan^-1(5/8)

• Lags the voltage by tan^-1(3/4)

• Lags the voltage by tan^-1(5/8)

Which of the following parameter in the series LCR circuit is analogous to driving force F(t) in mechanics?

• $\frac{{\mathrm{V}}_0}{\mathrm{L}}$

• inductance L

• capacitance C

• voltage V₀

What is the mechanical equivalent of spring constant kin LC oscillating circuit?

• $\frac{1}{\mathrm{L}}$

• $\frac{1}{\mathrm{C}}$

• $\frac{\mathrm{L}}{\mathrm{C}}$

• $\frac{1}{\mathrm{L} \mathrm{C}}$

Alternating current cannot be measured by D.C ammeter because

• A.C cannot pass through D.C parameter

• A.C changes direction

• average value of current for complete cycle is zero 

• D.C ammeter will get changed