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Which of the following circuit elements dissipates energy in an AC circuit?
The NCERT text clarifies: 'There are no power losses associated with pure capacitances and pure inductances in an ac circuit. The only element that dissipates energy in an ac circuit is the resistive element.'
What is a 'phasor' in the context of AC circuits?
The NCERT text defines it: 'A phasor* is a vector which rotates about the origin with angular speed $\omega$, as shown in Fig. 7.4. The vertical components of phasors V and I represent the sinusoidally varying quantities v and i.'
In a purely capacitive AC circuit, what is the phase relationship between the current and the applied voltage?
The NCERT text states: 'The current through the capacitor is $\pi/2$ ahead of the applied voltage.' Also, 'Thus, we see that in the case of an inductor, the current lags the voltage by $\pi/2$ and in the case of a capacitor, the current leads the voltage by $\pi/2$.'
What is the average power supplied to a purely capacitive AC circuit over one complete cycle?
The NCERT text explicitly states: 'So, as in the case of an inductor, the average power $\overline{P_C} = \frac{1}{2}i_m v_m \left<\sin(2\omega t)\right> = 0$ since $\left<\sin(2\omega t)\right> = 0$ over a complete cycle.'
When a DC source is connected to a capacitor, what happens to a lamp connected in series with it?
The NCERT example states: 'When a dc source is connected to a capacitor, the capacitor gets charged and after charging no current flows in the circuit and the lamp will not glow.'
In an AC circuit, what term is used to describe current that causes no power dissipation?
The NCERT text mentions: 'In a purely inductive or capacitive circuit, $\cos \phi = 0$ and no power is dissipated even though a current is flowing in the circuit. In such cases, current is referred to as a wattless current.'
For a series RLC circuit, resonance occurs when:
The NCERT text states: 'In a RLC circuit, resonance phenomenon occur when $X_L = X_C$ or $\omega_0 = \frac{1}{\sqrt{LC}}$'.
The power factor in an RLC circuit is a measure of:
The NCERT text states: 'The power factor in a RLC circuit is a measure of how close the circuit is to expending the maximum power.'
If a capacitor is connected to an AC source and its capacitance (C) is reduced, what happens to the brightness of a series-connected lamp?
From Example 7.3: 'Reducing C will increase reactance [capacitive reactance $X_C = 1/(\omega C)$] and the lamp will shine less brightly than before.'
According to the NCERT text, what is the relationship between the peak voltage ($v_m$) and peak current ($i_m$) for a purely resistive AC circuit?
From Eq. (7.3) in the NCERT text: '$v_m = i_m R$'. This is essentially Ohm's Law for peak values in a resistive AC circuit.
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.