Which of the following is expected to have the maximum permeability ?
Zinc
Copper
Brass
Ebonite
Ebonite
Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it
increases their cost of manufacture
leads to their increased weight
lowers their power efficiency
produces fringing
lowers their power efficiency
Relative permeability of vacuum is
1
4n x 10 H/m
1/4JI
1 H/m
1
Permanent magnets are normally made of
alnico alloys
cast iron
aluminium
wrought iron
alnico alloys
Energy stored by a coil is doubled when its current is increased by percent.
100
41.4
25
50
41.4
Those magnetic materials are best suited for making armature and transformer cores which have____permeability and_______hystersis loss.
high low
high high
low high
low low
high low
The rate of rise of current through an inductive coil is maximum
near the final maximum value of current
after one time constant
at 63.2% of its maximum steady value
at the start of the current flow
at the start of the current flow
A material which is slightly repelled by a magnetic field is known as
ferromagnetic material
paramagnetic material
diamagnetic material
conducting material
diamagnetic material
When an iron piece is placed in a magnetic field
the magnetic lines of force will bend away from their usual paths in order to pass through the piece
the iron piece will break
the magnetic field will not be affected
the magnetic lines of force will bend away from their usual paths in order to go away from the piece
the magnetic lines of force will bend away from their usual paths in order to pass through the piece
Fleming’s left hand rule is used to find
direction of force on a current carrying conductor in a magnetic field
direction of flux in a solenoid
direction of magnetic field due to current carrying conductor
polarity of a magnetic pole
direction of force on a current carrying conductor in a magnetic field
पोस्ट अच्छी लगी हो तो प्लीज नीचे दिए गए लिंक पर क्लिक कर शेयर जरुर करें
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