1. For a series or parallel LC circuit, resonance occurs when _______.
(A) XL = 10XC
(B) XC = 10XL
(C) XL = XC
(D) the phase angle of circuit is 90°
2. When either L or C is increased, the resonant frequency of the LC circuit _______.
(A) decreases
(B) Increases
(C) remains the same
(D) is determined by shunt R
3. The resonant frequency of an LC circuit is 1000KHz. If L is doubled and C is reduced to 1/8th, the resonant frequency is _______.
(A) 250KHz
(B) 500KHz
(C) 1000KHz
(D) 2000KHz
4. A coil has a 1000 Ω XL & 5 Ω Ri. Its Q equals _______.
(A) 200
(B) 5
(C) 500
(D) 1000
5. In a parallel LC circuit, at the resonant frequency, the _______.
(A) Line current is maximum
(B) Inductive branch current is minimum
(C) Total impedance is maximum
(D) Total impedance is minimum
6. At resonance, the phase angle equals _______.
(A) 0°
(B) 90°
(C) 180°
(D) 270°
7. In a series LC circuit, at resonant frequency, the _______.
(A) current is minimum
(B) Voltage across C is minimum
(C) Impedance is maximum
(D) Current is maximum
8. A series LC circuit has a Q of 100 at resonance. When 5mV is applied at resonant frequency, the voltage across C equals _______.
(A) 5mV
(B) 20mV
(C) 100mV
(D) 500mV
9. An LC circuit is resonant at 1000KHz & has a Q of 100. The bandwidth b/w half power points are _______.
(A) 5 KHz b/w 995 and 1000 KHz
(B) 10 KHz b/w 1000 and 1010 KHz
(C) 10 KHz b/w 995 and 1005 KHz
(D) 200 KHz b/w 900 and 1100 KHz
10. In a low Q parallel resonant circuit, when XL = XC _______.
(A) the phase angle is 0°
(B) IL < IC
(C) IL > IC
(D) IL = IC
11. Resonance curve shows variation of circuit current with _______.
(A) Voltage
(B) frequency
(C) band width
(D) all of these
12. Higher the Q-factor of a circuit _______ its bandwidth.
(A) Narrower
(B) Expansion
(C) Increase
(D) Widen
13. Lower the resistance of a resonant circuit, _______ its selectivity.
(A) Decrease
(B) Narrower
(C) Better
(D) Bad
14. Sharpness of tuning depends _______ on the Q of a coil.
(A) Maximum
(B) Minimum
(C) complete
(D) inversely
15. In parallel resonance, the line current is _______ at the resonant frequency.
(A) Maximum
(B) often
(C) complete
(D) Minimum
16. Bandwidth of a series resonant circuit depends on _______.
(A) C
(B) L
(C) R
(D) All of the above
17. The power factor of a resonant series circuit is _______.
(A) 0.5
(B) 6
(C) 1
(D) 1
18. Higher the Q factor of a series circuit _______.
(A) Greater its bandwidth
(B) Sharper its resonance curve
(C) Broader its resonance curve
(D) Narrower its pass band
19. As the Q factor of a circuit _______ its selectivity becomes _______.
(A) none of these
(B) increase, worse
(C) Decrease, better
(D) Increase, better