Choke MCQs
A choke coil is a used in electrical circuits to allow DC current to flow through and blocks AC currents.The choke coil works similar to that of an inductor. When current passing through choke changes, magnetic field is created by electromagnetic induction which again opposes the current.This ability of coil is known as self inductance. So that it can block AC currents but allows the DC currents to flow through it.These coils are used in a number of electrical devices, e.g. tube light.
The choke coil offers the resistance called as inductive reactance given by,
XL = ωL
The practical form of choke coil is a inductor connected in series with small resistance r, which adds more resistance to flow the current in the circuit.
The power consumed by choke can be given as
Pav = erms irms cos∅
Where cos∅ is power factor.
Q.1) In AC circuits, choke coil is used as……….
a) resistance
b) impedance
c) power factor
d) none of these
Q.2) Choke coil works on the principle of
a) self induction
b) mutual induction
b) either ‘a’ or ‘b’
d) neither ‘a’ nor ‘b’
Q.3) The reactance offered be choke coil of inductance 0.2 H for the AC current of frequency 40 Hz
a) 12.5 Ω
b) 25 Ω
c) 37.5 Ω
d) 50 Ω
XL = ωL = 2πfL = 2 × 3.14 × 40 × 0.2 = 50.24 Ω
Q.4) Due to choke coil, current in alternating circuit………
a) leads emf by phase of π/2
b) lags behind emf by phase of π/2
c) is in same phase of emf
d) all of these.
Q.5) The average power consumed by choke coil is given as…
a) Pav = erms irms Sin∅
b) Pav = erms irms cos∅
c) Pav = erms irms tan∅
d) Pav = erms irms cot∅
Q.6) Power consumed by choke coil of very small resistance, if connected across 200 volt supply and carries current of 2 mA
a) 0
b) 0.2 W
c) 0.4 W
d) 0.8 W
Q.7) Choke coil is used in……………
a) electric fan
b) tube lights
c) electric motors
d) all of these
Answers
Q.1) a) resistance
Q.2) a) self induction
Q.3) d) 50 Ω
Q.4) b) lags behind emf by phase of
Q.5) b) Pav = erms irms cos∅
Q.6) a) 0
Q.7) d) all of these
