(English Medium) ICSE Class 10 - CISCE Important Questions for Physics

Name a common device that uses electromagnets.

Name two factors on which the magnitude of an induced e.m.f. in the secondary coil depends.

In the following diagram an arrow shows the motion of the coil towards the bar magnet.
(1) State in which direction the current flows, A to B or B to A?
(2) Name the law used to come to the conclusion.

How is the e.m.f. across primary and secondary coils of a transformer related with the number of turns of the coil in them?

On which type of current do transformers work?

State any two advantages of electromagnets over permanent magnets.

The diagram shows a coil wound around a U shape soft iron bar AB.

1) What is the polarity induced at the ends A and B when the switch is pressed?

2) Suggest one way to strengthen the magnetic field in the electromagnet

3) What will be the polarities at A & B if the direction of current is reversed in the circuit?

Draw a diagram to represent the magnetic field lines along the axis of a current carrying solenoid. Mark arrows to show the direction of current in the solenoid and the direction of magnetic field lines.

State two ways to increase the speed of rotation of a D.C. motor.

A magnet kept at the centre of two coils A and B is moved to and fro as shown in the diagram. The two galvanometers show deflection. State with a reason whether : x > y or x< y    [x and y are magnitudes of deflection.]

Draw a neat labeled diagram of an A.C. generator 

A coil has a self-inductance of 0·05 Henry. Find the magnitude of the emf induced in it when the current flowing through it is changing at the rate of 100 As^-1.

Why is the core of a transformer made of soft iron?

The diagram below shows a free conductor AB is kept in a magnetic field and is carrying current from A to B. (To avoid confusion complete path of the circuit is not shown) The direction of the force experienced by the conductor will be:

The diagram below shows a magnet moved near a coil along its axis. Which of the diagram shows correct flow of current during this motion?

The diagram below shows an insulated copper wire wound around a hollow cardboard cylindrical tube. Answer the questions that follow:

1. What are the magnetic poles at A and B when the key K is closed?
2. State two ways to increase the strength of the magnetic field in this coil without changing the coil.
3. If we place a soft iron bar at the centre of the hollow cardboard and replace the DC source with an AC source then will it attract small iron pins toward itself when the current is flowing through the coil?

Name one electrical device which works on Faraday's law of electromagnetic induction principle.

If the strength of the current flowing through a wire is increased, the strength of the magnetic field produced by it ______.

A copper conductor is placed over two stretched copper wires whose ends ate connected to a D.C. supply as shown in the diagram.

1. What should be the magnetic poles at the points A and B lying on either side of the conductor to experience the force in the upward direction?
2. Name the law used to find these polarities.

State two factors affecting the coil's rotation speed in a D.C. motor.