Physics [1 Mark Question Answer]

A conductor is moved in a varying magnetic field. Name the law which determines the direction of current induced in the conductor.

In which of the following case does the electromagnetic induction occur?

A loop of wire is held near a magnet.

In which of the following case does the electromagnetic induction occur?

A magnet is moved through a loop of wire .

In which of the following case does the electromagnetic induction occur?
The current is stopped in a wire held near a loop of wire .

In which of the following case does the electromagnetic induction occur?

A current is started in a wire held near a loop of wire ?

What factor determines the direction of induced e.m.f?

Name the material of core in (a) electric bell, (b) electromagnet (c) d.c motor, (d) an a.c. generator and (e) transformer.

Name the phenomenon ?

What kind of energy change takes place when a magnet is moved towards a coil having a galvanometer at its ends?

Complete the following sentence:
In a step-up transformer, the number of turns in the primary are …………than the number of turns in the secondary.

Why is the iron core of a transformer made laminated (thin sheets) instead of being in one solid piece?

Name the device used to transform 12 V a.c. to 200V a.c. Name the principal on which it
works.

For what purpose are the transformers used? Can they be used with a direct current source?

What energy conversion does take place in a generator when it is in use?

Complete the sentence:

An a.c. generator changes the ___________ energy to ___________ energy.

What determines the frequency of a.c. produced in a generator?

Explain why an induced current must flow in such a direction so as to oppose the change producing it.

Why is it more difficult to move a magnet towards a coil which has large number of turns?

What is Lenz's law?

What is electromagnetic induction?

What is an electric motor?

A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.

Name an instrument which makes use of the principle stated above.

A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.

When will coil come to rest?

A flat coil ABCD is freely suspended between the pole pieces of U-Shaped permanent magnet with the plane of coil parallel to the magnetic field.
What happens when a current is passed in the coil ?

State the unit of magnetic field in terms of the force experienced by a current carrying conductor placed in a magnetic field

How will the direction of force be changed, if the current is reversed in the conductor placed in a magnetic field?

State condition when magnitude of force on a current carrying conductor placed in a magnetic field is maximum ?

State condition when magnitude of force on a current carrying conductor placed in a magnetic field is Zero ?

Name two appliances in which an electric motor is used.

What energy conversion does take place during the working of a d.c. motor?

What is the direction of magnetic field at the centre of a coil carrying current in anticlockwise direction?

What is the direction of magnetic field at the centre of a coil carrying current in clockwise ?

A wire, bent into a circle, carries current in an anticlockwise direction. What polarity does this face of the coil exhibit?

Name the material used for making the armature of an electric bell. Give a reason for your answer.

How is the magnetic field due to a straight current carrying wire affected if current in wire is reversed?

How is the magnetic field due to a straight current carrying wire affected if current in wire is decreased ?

Name one device that uses an electromagnet.

In following figure shows the current flowing in the coil of wire wound around the soft iron horse shoe core.Suggest one way increase the strength of magnetic filed produce.

In following figure shows the current flowing in the coil of wire wound around the soft iron horse shoe core.How will the polarity at the ends A and B change on reversing the direction of current.

In following Figure shows the current flowing in the coil of wire wound around the soft iron horse shoe core. State the polarities developed at the ends A and B.

What is an electromagnet?

The adjacent diagram shows a coil would around a soft iron bar XY. (a) State the polarity at the end X and Y as the switch is pressed. (b) Suggest one way increasing the strength of electromagnet so formed.

How is the magnetic field due to a solenoid carrying current affected if a soft iron bar is introduced inside the solenoid?

What effect will there be on magnetic compass when it is brought near a current carrying solenoid?

Why does a current carrying freely suspended solenoid rest along a particular direction?