151. The core of a transformer heats up when its primary is fed from an ac source because of
A. permeability
B. ferromagnetism
C. reluctance of core D. hysteresis loss
152. Which of the following materials has the least hysteresis loop area?
A. soft iron
B. silicon steel
C. hard steel
D. wrought iron
153. Core materials of a good relay have hysteresis loop.
A. large
B. narrow
C. very large
D. very narrow
154. The magnetic materials should have a large hysteresis loss for one of the following
applications.
A. Transformers
B. AC motors
C. Permanent Magnets
D. DC generators
155. If the magnetic material is located within a coil through which alternating current (60 Hz
frequency) flows, then hysteresis loops will be formed every second.
A. 60
B. 120
C. 30
D. 180
, 156. There are how many compounds available in nature? A. 105
B. 1000
C. 300,000
D. Unlimited
157. Hysteresis is a phenomenon of in a magnetic circuit.
A. setting up constant flux
B. lagging of H behind B C. lagging B behind H
D. leading B ahead H
158. What is the measure of the density and sign of the electric charge at a point relative to that
at some time?
A. Electric potential
B. Electric charge
C. Electric current
D. Electric intensity
159. is a substance of whose molecules consist of the same kind of atom.
A. Mixture
B. Compound C. Element
D. Isotope
160. Hipernik is an alloy containing iron and nickel. A. 40% ; 60%
B. 60% ; 40%
C. 50% ; 50%
D. 70% ; 30%
161. The mass of proton is the mass of an electron.
A. equal to
B. about 1837 times
C. less than
D. 200 times
A. permeability
B. ferromagnetism
C. reluctance of core D. hysteresis loss
152. Which of the following materials has the least hysteresis loop area?
A. soft iron
B. silicon steel
C. hard steel
D. wrought iron
153. Core materials of a good relay have hysteresis loop.
A. large
B. narrow
C. very large
D. very narrow
154. The magnetic materials should have a large hysteresis loss for one of the following
applications.
A. Transformers
B. AC motors
C. Permanent Magnets
D. DC generators
155. If the magnetic material is located within a coil through which alternating current (60 Hz
frequency) flows, then hysteresis loops will be formed every second.
A. 60
B. 120
C. 30
D. 180
, 156. There are how many compounds available in nature? A. 105
B. 1000
C. 300,000
D. Unlimited
157. Hysteresis is a phenomenon of in a magnetic circuit.
A. setting up constant flux
B. lagging of H behind B C. lagging B behind H
D. leading B ahead H
158. What is the measure of the density and sign of the electric charge at a point relative to that
at some time?
A. Electric potential
B. Electric charge
C. Electric current
D. Electric intensity
159. is a substance of whose molecules consist of the same kind of atom.
A. Mixture
B. Compound C. Element
D. Isotope
160. Hipernik is an alloy containing iron and nickel. A. 40% ; 60%
B. 60% ; 40%
C. 50% ; 50%
D. 70% ; 30%
161. The mass of proton is the mass of an electron.
A. equal to
B. about 1837 times
C. less than
D. 200 times
