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The RMS value of current ($I_{rms}$) in an AC circuit is defined such that it:
The NCERT text states: 'Joule heating is such a property, and there is one ampere of rms value of alternating current in a circuit if the current produces the same average heating effect as one ampere of dc current would produce under the same conditions.'
If the household line voltage is specified as 220 V, what does this value typically represent?
The NCERT text highlights, 'It is customary to measure and specify rms values for ac quantities. For example, the household line voltage of 220 V is an rms value...'
For a sinusoidal AC voltage $v = v_m \sin(\omega t)$, the RMS voltage ($V$) is given by:
According to the NCERT text, 'V = $v_m / \sqrt{2}$ = 0.707 $v_m$ (7.8)'.
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 $\omega_0 = \frac{1}{\sqrt{LC}}$'.
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.