2nd Year Physics Chapter 15 Online MCQ Test for 12th Class Physics Chapter 15 (Electromagnetic Induction)

The jerks in D.C. motor are created by the use of.

• Armature A
• Commutators B
• Split rings C
• Source of emf D

If force in the direction of velocity of conductor,  then induced current is directed,

• Anti clockwise A
• Clock wise B
• At equilibrium C
• None of above D

Energy density of an inductor is:

• UM=1/2μ_∘/B² A
• Um = 2μ_∘/B B
• UM = 1/2B²/μ_∘ C
• Um = 2B²/μ_∘ D

For inducing emf in a coil the basic requirement is that:

• Flux should link the coil A
• Change in flux should link the coil B
• Coil should form a closed loop C
• Both (b) and (c) are true D

The induced emf in a coil is proportional to:

• Magnetic flux through the coil A
• Rate of change of Magnetic flux through the coil B
• Area of the coil C
• Product of magnetic flux flux and area of the coil D

Energy stored in an inductor is:

• 1/2L²I A
• 1/2L²/I B
• _1/2LI² C
• 1/2LI D

If the coil is wound on iron core, the flux through it.

• Decreases A
• Becomes zero B
• Increases C
• Remains constant D

When the back emf in a current is zero, it draws

• Zero current A
• Maximum current B
• Minimum current C
• Steady average current D

The winding of the electromagnet in motor are usually called.

• Magnetic coils A
• Field coils B
• Electric coils C
• electric o electric coils D

A step up transformer is used 120 V line to provide 240 V. If primary coil has 100 turns the number of turns is secondary is.

• 50 A
• 100 B
• 150 C
• 200 D

The direction of induced current is always so as to oppose the change which causes the current, this is the statement of

• Lenz's law A
• Faraday's law B
• Ampere's law C
• Coulomb's law D

The magnitude of motional emf is given by

• 
  A
• 
  B
• 
  C
• 
  D

Michael Faraday and Joseph Henry belongs to

• England and USA A
• France and USA B
• China and USA C
• None of these D

With the speed of motor, magnitude of back emf

• Remain same A
• Increase B
• Decrease C
• First increases then decreases D

The illustration of the phenomenon of mutual induction is in the device of

• Transformer A
• Inductor B
• A.C. Generator C
• Ammeter D

The  Lenz's law is also statement of:

• Law of conservation of mass A
• Law of conservation of charge B
• Law of conservation of energy C
• Law of conservation of momentum D

• Lenz's law A
• Faraday's law B
• Ampere's law C
• None of these D