Physics English Medium

# 7. ALTERNATING CURRENT( Objective Question Answer 2022 )

1. Power factor of an ac circuit is a measure of:

(A) virtual power
(B) power lost in the circuit
(C) mean power
(D) all the above

2. The dimensional formula of L/R is similar to that of:

(A) frequency
(B) time
(C) length
(D) none of these

3. Which of the following has dimensions different from the rest ?

(A) L/R
(B) 1/RC
(C) √LC
(D) RC

4. The dimensional formula of impedance is :

(A) [ML2T-2A-2]
(B) [ML2T-3A-2]
(C) [ML2T-2A-1]
(D) [ML2T-2A-3]

5. Energy dissipates in LCR circuit in:

(A) L only
(B) C only
(C) R only
(D) All of the above

6. A choke is used as a resistance in :

(A) de circuits
(B) ac circuits
(C) both ac and dc circuits
(D) neither (A) nor (B)

7. The SI unit of magnetic flux is :

(A) T
(B) Tn-2
(C) Wb
(D) Wb m-2

8. For purely capacitive circuits, power factor is :

(A) O
(B) -1
(C) 1
(D) infinity

9. The magnetic flux linked with a coil is inversely proportional to the :

(A) magnetic field
(B) area of cross section
(C) number of turns
(D) none of these

10. When the magnetic field is parallel to a surface, then the magnetic flux through the surface is :

(A) infinite
(B) zero
(C) small but not zero
(D) large but not infinite

11. The dimensional formula of induced emf is :

(A) [ML2T-2A-1]
(B) [ML2T-3A-1]
(C) [ML2T-3A-2]
(D) [ML2T-2A-2]

12. The dimensional formula of the coefficient of self inductance is :

(A) [ML2T-2]
(B) [ML2T-3A-1]
(C) [ML2T-2A-2]
(D) [ML2T-3A-2]

13. The motional emf produced across moving through a magnetic field does depend on its:

(A) length
(B) velocity
(C) orientation
(D) diameter

14. What is the ratio of inductive and capacitance reactances in an ac circuit ?

(A) 1
(B) ω2L
(C) ω2LC
(D) 1

15. An acceptor circuit is :

(A) series resonant circuit
(B) parallel resonant circuit
(C) LCR circuit
(D) None of these

16. In series resonant circuit :

(A) reactance is zero
(B) current is zero
(C) voltage is zero
(D) None of these

17. In parallel resonant circuit ;

(A) impedance is very high
(B) current is very high
(C) voltage is very high
(D) None of these