Magnetic Effects of Electric Current Class 10

Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.

The phenomenon of electromagnetic induction is
the process of charging a body.
the process of generating magnetic field due to a current passing through a coil.
producing induced current in a coil due to relative motion between a magnet and the coil.
the process of rotating a coil of an electric motor

The device used for producing electric current is called a
generator.
galvanometer.
ammeter.
motor.

The essential difference between an AC generator and a DC generator is that
AC generator has an electromagnet while a DC generator has
permanent magnet.
DC generator will generate a higher voltage.
AC generator will generate a higher voltage.
AC generator has slip rings while the DC generator has a commutator.

At the time of short circuit, the current in the circuit
reduces substantially.
does not change.
increases heavily.
vary continuously.

State whether the following statements are true or false.
(a) An electric motor converts mechanical energy into electrical energy.

List two methods of producing magnetic fields.

How does a solenoid behave like a magnet? Can you determine the north and south poles of a current–carrying solenoid with the help of a bar magnet? Explain.

When is the force experienced by a current–carrying conductor placed in a magnetic field largest?

Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?

Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split ring in an electric motor?

Name some devices in which electric motors are used.

A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (i) pushed into the coil, (ii) withdrawn from inside the coil, (iii) held stationary inside the coil?

Two circular coils A and B are placed close to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.

State the rule to determine the direction of a
(i) magnetic field produced around a straight conductor-carrying current,
(ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and
(iii) current induced in a coil due to its rotation in a magnetic field.

Explain the underlying principle and working of an electric generator by drawing
a labelled diagram. What is the function of brushes?

When does an electric short circuit occur?

What is the function of an earth wire? Why is it necessary to earth metallic appliances?

Why does a compass needle get deflected when brought near a bar magnet?

Draw magnetic field lines around a bar magnet.

List the properties of magnetic field lines.

Why don’t two magnetic field lines intersect each other?

Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.

The magnetic field in a given region is uniform. Draw a diagram to represent it.

The magnetic field inside a long straight solenoid-carrying current
is zero.
decreases as we move towards its end.
increases as we move towards its end.
is the same at all points.

In Activity 13.7, how do we think the displacement of rod AB will be affected if (i) current in rod AB is increased; (ii) a stronger horse-shoe magnet is used; and (iii) length of the rod AB is increased?

A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
(a) towards south
(b) towards east
(c) downward
(d) upward

State Fleming’s left-hand rule.

What is the principle of an electric motor?

What is the role of the split ring in an electric motor?

Explain different ways to induce a current in a coil.

State the principle of an electric generator.

Name some sources of direct current.

Which sources produce alternating current?

A rectangular coil of copper wire is rotated in a magnetic field. The direction of the induced current changes once in each
(a) two revolutions (b) one revolution
(c) half revolution (d) one-fourth revolution

Name two safety measures commonly used in electric circuits and appliances.

An electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain.

What precautions should be taken to avoid the overloading of domestic electric circuits?

Which of the following property of a proton can change while it moves freely in a magnetic field? (there may be more than one correct answer.)
(a) Mass (b) Speed
(c) velocity (d) momentum

A current through a horizontal power line flows in east to west direction. What is the direction of magnetic field at a point directly below it and at a point directly above it?

An electron enters a magnetic field at right angles to it, as shown in Fig. 13.14. The direction of force acting on the electron will be
(a) to the right.
(b) to the left.
(c) out of the page.
(d) into the page.