# Multiple Choice Question (MCQ) of Measurements page-16

151. In the moving iron instruments, the torque is proportional to

a) Inductance of instruments
b) First derivative of inductance with respect to time
c) First derivative of inductance of instruments with respect to deflection angle
d) Current

Ans: (c)

152. Which of the instrument are free from hysteresis and eddy current losses?

a) Moving iron instruments
b) Electrodynameter type instruments
c) Electrostatic instruments
d) None of the above

Ans: (c)

153. The electrostatic instruments rely for their operation upon the

a) Current
b) Voltage
c) Fact that a force exists between the two plates having opposite charges
d) Power

Ans: (c)

154. Which of the following instruments can be used to measure only A.C. currents?

a) Moving iron instruments
b) Electrodynamic instruments
c) Induction type instruments
d) Hotwire instruments

Ans: (c)

155. The permeability of magnetic circuits is analogous to

a) Current of electrical circuits
b) Voltage of electrical circuits
c) Current density of electrical circuits
d) Resistance of electrical circuits
e) Conductivity of electrical circuits

Ans: (e)

156. The current ratio of current transformers is constant under all load conditions.

a) True
b) False

Ans: (b)

157. The ratio error in the current transformers is largely dependent upon

a) Iron loss component of magnetizing current
b) Magnetizing component of the magnetizing current
c) (a) and (b) both
d) (a) or (b)

Ans: (a)

158. The material used for the core of current transformer should have

a) Low reluctance and low iron loss
b) High reluctance and high iron loss
c) Low reluctance and high iron loss
d) High reluctance and low iron loss

Ans: (a)

159. What will happen if the secondary winding of the current transformer is opened when current is flowing in the primary current?

a) There will be high current in the secondary winding
b) There will be very high induced voltage in the secondary winding
c) There will be very weak flux density in the core
d) The transformer will burn immediately

Ans: (b)

160. Which of the secondary winding of current transformer is opened, the ampere-turns of primary winding will

a) Increase
b) Decrease
c) Remain same
d) Be very small

Ans: (c)