# Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-10

136. The initial permeability of an iron rod is

a) The permeability at the end of an iron rod
b) The permeability almost in non-magnetised state
c) The lowest permeability of iron rod
d) The highest permeability of iron rod

Ans: (b)

137. The magnetic reluctance of a material

a) Increases with increasing cross-sectional area of material
b) Decreases with increasing cross-sectional area of material
c) Does not vary with increasing cross-sectional area of material
d) Does vary from small increase in cross-sectional area of the material

Ans: (b)

138. The magnetic field strength H and magnetic induction B are independent of each other.

a) True
b) False

Ans: (b)

139. Which part of the magnetic path requires largest MMF?

a) Core
b) Air gap
c) Coil
d) Inductance

Ans: (b)

140. The presence of magnetic field can be determined by

a) Detecting the lines of magnetic flux
b) Deflection of a magnetic compass needle
c) Heating the surrounding air
d) Touching the magnetically affected area

Ans: (b)

141. How does the magnetic compass needle behave in a magnetic field?

a) It starts rotating
b) It assures a position right angle to magnetic field
c) It assures a position which follows a line of magnetic flux
d) None of the above

Ans: (c)

142. The magnetic reactance has the same unit as electric reactance.

a) True
b) False

Ans: (b)

143. MMF is analogous to

a) Electric current in electrical circuit
b) Electromotive force
c) Current density in conductor
d) Voltage

Ans: (b)

144. Which of the following statements is correct?

a) The strength of magnetic flux in a simple magnetic field continuously increases from initial value of final value.
b) The strength of magnetic flux in a simple magnetic field continuously decreases from initial value to final value.
c) The strength of magnetic flux in simple magnetic field is constant and has same value in every part of the magnetic field.
d) None of the above statements is correct.

Ans: (c)

145. There is no existence of such material which is completely impermeable to magnetic flux.

a) True
b) False

Ans: (a)

146. The stray line of magnetic flux is defined as

a) A line of magnetic flux in a non-uniform field
b) A line of magnetic flux which does not follow the designed path
c) The mean length of a right shaped coil
d) A line vertical to the flux lines

Ans: (b)

147. In the given circuit, the voltage V is reduced to half. The current I will change to

a) 2I
b) I/2
c) I/[ √R2 + (XL- XC )]
d) I/[√(XL- XC )2 )]
Ans: (b)

148. The current in the loaded battery flows from

a) + ve to – ve plate
b) – ve to + ve plate
c) Between plates
d) Between terminals

Ans: (b)

149. In the circuit shown, the current in the resistance 1 shall be

a) 3/7I
b) 3/4I
c) I
d) 7/3I
e) 1/4I

Ans: (a)

150. The four bulbs of 40 watts each are connected in series with a battery across them, which of the following statements is true?

a) The voltage across each bulb is same
b) The power dissipation in each bulb is not same
c) The current through each bulb is same
d) None of the above

Ans: (c)