AIIMS Physics Alternating Current Class 12 Questions

Frequency of L-C circuit is $f_1$. If a resistance R is also added to it, the frequency becomes $f_2$. The ratio of $\frac{f_2}{f_1}$ will be:

Assertion : When the frequency of the AC source in an LCR circuit equals the resonant frequency, the reactance of the circuit is zero, and so there is no current through the inductor or the capacitor. Reason : The net current in the inductor and capacitor is not zero.

A series R-C circuit is connected to an AC voltage source. Consider two cases: (A) when C is without a dielectric medium and (B) when C is filled with a dielectric of constant 4. The current $I_R$ through the resistance and voltage $V_C$ across the capacitor are compared in the two cases. Which of the following is true?

Assertion: The average value of alternating emf is 63.39% of the peak value. Reason: The rms value of alternating emf is 70.72% of peak value.

A series resonant LCR circuit has a quality factor (Q⁻factor) 0.4. If R = 2 kΩ, C = 0.01 μF, then the value of inductance is

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.

A condenser of 250 μF is connected in parallel to a coil of inductance 0.16 mH, while its effective resistance is 20 Ω. Determine the resonant frequency.

Assertion (A) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

Assertion (A) If the frequency of the applied AC is doubled, then the power factor of a series R⁻L circuit decreases. Reason (R) Power factor of series R⁻L circuit is given by \( \cos \theta = \frac{2R}{\sqrt{R^²⁺ \omega^2 L^2}} \)

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

In a given series LCR circuit R = 4 Ω, XL = 5 Ω and XC = 8 Ω, the current

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

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

In series LCR circuit, the phase difference between applied voltage and current is

Alternating current cannot be measured by D.C. ammeter because

Reciprocal of impedance is

In a series LCR circuit, the voltage across the resistance, capacitance and inductance is 10 V each. If the capacitance is short circuited the voltage across the inductance will be

If frequency of R – L circuit is f then impedance will be

A bulb and a condenser are connected in series with an A.C. source. On increasing the frequency of the source its brightness will

When 100 V d.c. is applied across a coil, a current of 1 Å flows through it. When 100 V a.c. of 50 Hz is applied to the same coil only 0.5 Å flows. The inductance of the coil is

In an AC circuit the potential differences across an inductance and resistance joined in series are respectively 16 V and 20 V. The total potential difference of the source is

Assertion : No power loss associated with pure capacitor in ac circuit. Reason : No current is flowing in this circuit.

Assertion: The quantity $L/R$ possesses dimension of time. Reason: To reduce the rate of increase of current through a solenoid, we should increase the time constant ($L/R$).

If in a circuit current lags behind EMF by π/2. Then it is a/an

In a series LCR circuit the voltage across resistance, capacitance and inductance is 10 V each. If the capacitance is short circuited, the voltage across the inductance will be