Q.1
Relative permeability of vacuum is
  • 1
  • 1 H/m
  • 1/4JI
  • 4n × 10' H/m
Q.2
The initial rate of rise of current through a coil of inductanceH when suddenly connected to a D.C. supply ofV is ___________Vs
  • 50
  • 20
  • 0.05
  • 500
Q.3
Those magnetic materials are best suited for making armature and transformer cores which have ________permeability and _________hysteresis loss.
  • High, high
  • Low, high
  • High, low
  • Low, low
Q.4
While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit?
  • E.M.F.
  • Current
  • Current density
  • Conductivity
Q.5
Those materials are well suited for making permanent magnets which have ________ retentivity and ________ coercivity.
  • Low, high
  • High, high
  • High, low
  • Low, low
Q.6
Laminated cores, in electrical machines, are used to reduce
  • Copper loss
  • Eddy current loss
  • Hysteresis loss
  • All of the above
Q.7
The unit of magnetic flux is
  • Henry
  • Weber
  • Ampere-turn/weber
  • Ampere/metre
Q.8
Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it
  • Lowers their power efficiency
  • Increases their cost of manufacture
  • Leads to their increased weight
  • Produces fringing
0 h : 0 m : 1 s