11) A permanent magnet should have
a) low remanence
b) high remanence
c) zero remanence
d) none of the above
12) The relative permeability of air is
a) 0
b) 1
c) infinite
d) none of the above
13) The curie tempareture of iron is
a) 2000C
b) 4300C
c) 7000C
d) 5500C
14) In practical magnetic circuits, the air-gap is kept
a) very small
b) large
c) very large
d) none of the above
15) An electromagnet uses
a) soft iron core
b) steel core
c) nickel core
d) copper core
16) The magnetic potential difference in a magnetic circuit is given by
a) H/I
b) B X I
c) HI
d) BI X h
17) The hysteresis loop of a material that cannot be magnetized easily is
a) narrow
b) very narrow
c) wide
d) none of the abve
18) The hysteresis loop is nearly square for
a) iron core
b) steel core’
c) ferrite core
d) wrought iron core
19) Due to fringing at the air gaps in a magnetic circuit, the effective area of the air gaps is
a) increased
b) decreased
c) same
d) none of the above
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