RESONANCE MCQs 19 min Score: 0 Attempted: 0/19 Subscribe 1. For a series or parallel LC circuit, resonance occurs when _______. (A) XL = 10XC (B) XL = XC (C) XC = 10XL (D) The phase angle of circuit is 90° 2. When either L or C is increased, the resonant frequency of the LC circuit _______. (A) Increases (B) Is determined by shunt R (C) Remains the same (D) Decreases 3. The resonant frequency of an LC circuit is 1000 KHz. If L is doubled and C is reduced to 1/8th, the resonant frequency is _______. (A) 250 KHz (B) 500 KHz (C) 2000 KHz (D) 1000 KHz 4. A coil has a 1000 Ω XL & 5 Ω Ri. Its Q equals _______. (A) 1000 (B) 5 (C) 500 (D) 200 5. In a parallel LC circuit, at the resonant frequency, the _______. (A) Line current is maximum (B) Total impedance is maximum (C) Total impedance is minimum (D) Inductive branch current is minimum 6. At resonance, the phase angle equals _______. (A) 270° (B) 90° (C) 180° (D) 0° 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 5 mV is applied at resonant frequency, the voltage across C equals: (A) 5 mV (B) 500 mV (C) 100 mV (D) 20 mV 9. An LC circuit is resonant at 1000 KHz & has a Q of 100. The bandwidth between half power points is _______. (A) 10 KHz b/w 995 and 1005 KHz (B) 10 KHz b/w 1000 and 1010 KHz (C) 5 KHz b/w 995 and 1000 KHz (D) 200 KHz b/w 900 and 1100 KHz 10. In a low Q parallel resonant circuit, when XL = XC _______ (A) IL = IC (B) IL < IC (C) The phase angle is 0° (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) Expansion (B) Narrower (C) Increase (D) Widen 13. Lower the resistance of a resonant circuit, _______ its selectivity. (A) Better (B) Narrower (C) Decrease (D) Bad 14. Sharpness of tuning depends _______ on the Q of a coil. (A) Minimum (B) Complete (C) Maximum (D) Inversely 15. In parallel resonance, the line current is __ at the resonant frequency. (A) Maximum (B) Often (C) Complete (D) Minimum 16. Band width of a series resonant circuit depends on -- (A) R (B) L (C) C (D) All of the above 17. The power factor of a resonant series circuit is ___ (A) 1 (B) 6 (C) 1 (D) 0.5 18. Higher the Q factor of a series circuit _______. (A) Greater its bandwidth (B) Broader its resonance curve (C) Sharper its resonance curve (D) Narrower its pass band 19. As the Q factor of a circuit _______ its selectivity becomes _______. (A) Decrease, better (B) Increase, worse (C) Increase, better (D) None of these