Q.151 what will be the field at the center of circle, if two ends of a uniform circular wire are joined to the terminals of a battery
A. will depends on the amount of current
A. will depends on the amount of current
B. will depends on the radius of the circle
C. Both A and B
D. will depends on the voltage
Ans.: C
Q.152 Consider an infinite long straight conductor in which an electric current is flowing. The magnetic field at a distance of 4cm from the wire is 0.6 gauss. What will be the magnetic field at a distance of 2 cm from the wire?
A. 1.9 gauss
B. 12 gauss
C. 0.3 gauss
D. 1.2 gauss
Ans.: D
Q.153 The parallel conductor of 10 m long and of 10 mm diameter each carrying 100 A in opposite directions are separated by an air space of 50 mm. What will be the force on each conductor?
A. 0.033 N
B. 0.066 N
C. 0.99 N
D. 0.33 N
Ans.: A
Q.154 A material commonly used for screening or shielding magnetism is __.
A. brass
B. copper
C. tungsten
D. soft iron
Ans.: D
Q.155 The most effective and quickest way of making a magnet from soft iron is___
A. by placing it inside a current carrying coil
B. by rubbing
C. by the use of permanent magnet
D. by induction
Ans.: A
Q.156 what will be the magnetic field around each portion of the wire, if a wire carrying current is bent in the form of a circular loop?
A. perpendicular to half portion
B. parallel to half portion
C. parallel to the circumference of the circle
D. perpendicular to the circumference of the wire
Ans.: C
Q.157 Earth’s magnetic field always has a horizontal component except.
A. the magnetic poles
B. the equator
C. the geographical poles
D. magnetic neutral axis
Ans.: A
Q.158 What will be the magnetic moment of each piece of magnet, if a rectangular magnet of magnetic moment M is cut into two pieces of same length?
A. 2M
B. M/2
C. M/4
D. M
Ans.: B
Q.159 A copper disc is rotated rapidly below freely suspended magnetic needle. The magnetic needle starts rotating with velocity___
A. less than that of disc but in opposite direction
B. less than that of disc but in same direction
C. equal to that of disc and in the same direction
D. equal to that of disc and in the opposite direction
Ans.: B
Q.160 A solenoid has a flux of 12 m Wb and a flux density of 0.9 tesla. The inside diameter of the solenoid must be___.
A. 130 cm
B. 0.13 cm
C. 20 cm
D. 13 cm
Ans.: D
Q.161 In which of the following, hard magnetic materials are used?
A. in relay
B. in C.B
C. in making permanent magnets
D. transformer
Ans.: C
Q.162 Inductance: Reluctance::
A. Henry: AT/ Weber
B. Ohm: mho
C. Farad: Weber
D. Ampere: Ampere turn
Ans.: A
Q.163 Magnetic moment is ___.
A. vector quantity
B. universal quantity
C. scalar quantity
D. field strength
Ans.: A
Q.164 A keeper is used to__.
A. change the direction of electric field
B. provide a closed path for flux
C. help in induced emf
D. increase field strength
Ans.: B
Q.165 what is the total flux, if the iron core within a solenoid has a cross sectional are of 2 cm2 and flux density within the iron is 0.8 Tesla?
A. 0.016 mWb
B. 16 mWb
C. 1.6 mWb
D. 0.16 mWb
Ans.: D