Electrical Engineering Questions and Answers


91)

The winding resistance of a coil can be increased by

Answer: Option D

Explanation:

R = PL/A.
R = Resistance.
L= length of wire (wire is wound in, to form coil and number of coils connected in series gives winding)- directly proportional to resistance.

A= Area of cross section - inversely proportional to resistance.

As number of turns increases the length of coil also increases and
using a thinner wire gives lesser area of cross section.

Thus answer is D.
92)

An inductor, a 1 kΩ resistor, and a switch are connected in series across a 6 V battery. At the instant the switch is closed, the inductor voltage is

Answer: Option B

Explanation:
93)

wo inductors, L1 and L2, are in parallel. L1 has a value of 25 μH and L2 a value of 50 μH. The parallel combination is in series with L3, a 20 μH coil. The entire combination is across an ac source of 60 Vrms at 300 kHz. The total rms current is

Answer: Option B

Explanation:

Combination will be L=(25*50/75)+20=36.6

XL=2*Pi*f*L=2*3.14*300*1000*36.6*(1/1000000 )=68(approx)

current=V/XL=60/68=.87=870mA
94)

An ohmmeter is connected across an inductor and the pointer indicates zero ohms. The inductor is

Answer: Option C

Explanation:

if the inductor is shorted, inductor will offers zero impedance to current hence the current will not pass through the ohmmeter which has a resistance in it.hence the pointer will not operate at that condition
95)

A sine wave voltage is applied across an inductor. When the frequency of the voltage is decreased, the current

Answer: Option A

Explanation:

In pure inductor
I=V/XL,whereXL is inductive reactance
XL=2pifl

As f decreases XL also decreases thus I(CURRENT) increases

Similar CBTs


Popular CBTs