Questions and answers for exam Preparation

MCQs

Total Questions : 149 | Page 14 of 15 pages

Question 131. . A voltage is induced in a transformer secondary winding by the action of the:

secondary magnetic field
primary turns ratio
primary magnetic field
secondary counter emf

Discuss Question

Answer: Option C. -> primary magnetic field

Question 132. . The time required for one weber of flux to cut a conductor and produce one volt is:

one revolution
one second
one millisecond
four revolutions

Discuss Question

Answer: Option B. -> one second

Question 133. . In a transformer, what will happen to the primary current if the secondary magnetic field increases?

Ip will increase.
Ip will be canceled.
Ip will remain the same.
Ip will decrease.

Discuss Question

Answer: Option A. -> Ip will increase.

Question 134. . Counter emf or induced voltage is:

inversely proportional to the change in current
directly proportional to the change in time
directly proportional to the inductance in henrys
inversely proportional to the inductance in henrys

Discuss Question

Answer: Option C. -> directly proportional to the inductance in henrys

Question 135. . What is the phase angle between the source voltage and current, when a 100 mH inductor with a reactance of 6 komega.gif, and a 1 komega.gif resistor are in series with a source?

0.1 degrees
9.0 degrees
61.0 degrees
81.0 degrees

Discuss Question

Answer: Option D. -> 81.0 degrees

Question 136. . When a load is not connected to the secondary of a transformer:

primary current is zero
primary current is inversely proportional to primary impedance
secondary voltage is zero
secondary voltage is proportional to primary impedance

Discuss Question

Answer: Option B. -> primary current is inversely proportional to primary impedance

Question 137. . What are the properties that determine the inductance of a coil?

Length of wire, number of turns, type of core material, length of core
Number of turns, type of wire, length of core, and cross-sectional area of core
Type of core material, number of turns, cross-sectional area of core, and length of core
Type of core material, type of wire, number of turns, and cross-sectional area of core

Discuss Question

Answer: Option C. -> Type of core material, number of turns, cross-sectional area of core, and length of core

Question 138. .
An inductor is in series with a voltage source, an open switch, and a resistor. The instant the switch is closed, the inductor acts like