Advertisements
Advertisements
Question
The selectivity of a series LCR a.c. circuit is large, when ______.
Options
L is large and R is large.
L is small and R is small.
L is large and R is small.
L = R
Advertisements
Solution
The selectivity of a series LCR a.c. circuit is large, when L is large and R is small.
Explanation:
Selectivity of a circuit depends on the quality of resonance. The quality factor is given by:
Q = `(w_0 L)/R`
A high value of the quality factor ensures that the resonance curve is sharp. The sharper the resonance curve, the more selective the LCR circuit is. Thus, the selectivity of the LCR circuit is large when L is large and R is small. Hence, the L is large, and R is small.
RELATED QUESTIONS
An LR circuit contains an inductor of 500 mH, a resistor of 25.0 Ω and an emf of 5.00 V in series. Find the potential difference across the resistor at t = (a) 20.0 ms, (b) 100 ms and (c) 1.00 s.
Consider the circuit shown in figure. (a) Find the current through the battery a long time after the switch S is closed. (b) Suppose the switch is again opened at t = 0. What is the time constant of the discharging circuit? (c) Find the current through the inductor after one time constant.
In a series, LCR circuit, obtain an expression for the resonant frequency.
Using the phasor diagram, derive the expression for the current flowing in an ideal inductor connected to an a.c. source of voltage, v= vo sin ωt. Hence plot graphs showing the variation of (i) applied voltage and (ii) the current as a function of ωt.
If an LCR series circuit is connected to an ac source, then at resonance the voltage across ______.
In an LCR series a.c. circuit, the voltage across each of the components, L, C and R is 50V. The voltage across the LC combination will be ______.
The resonant frequency of a RF oscillator is 1 MHz and its bandwidth is 10 kHz. The quality factor will be :
For an LCR circuit driven at frequency ω, the equation reads
`L (di)/(dt) + Ri + q/C = v_i = v_m` sin ωt
- Multiply the equation by i and simplify where possible.
- Interpret each term physically.
- Cast the equation in the form of a conservation of energy statement.
- Integrate the equation over one cycle to find that the phase difference between v and i must be acute.
To reduce the resonant frequency in an L-C-R series circuit with a generator ______.
In the given circuit, rms value of current (Irms) through the resistor R is:
