Magnetic Effects of Electric Current
Important Questions Class 10 Science
Short Answer Type Questions [II] [3 Marks]
1.Describe an activity to show that the magnetic field lines produced when
current is passed through the circular coil.
Answer.
Aim : To study the characteristics of magnetic field produced by a current carrying
circular coil at its centre.
Apparatus Required : Rectangular cardboard having two holes, Thick copper
circular coils of different radii having known number of turns, key, battery, rheostat,
stand, iron filings.
Procedure :
1. Pass the coil through the two holes of cardboard in such a way that half
of the loop is above the cardboard and remaining part should be below it
and normal to the plane of cardboard.
2. Connect the circuit as shown.
3. Sprinkle iron filings uniformly on the cardboard.
4. Allow the current to pass though the coil by inserting plug in the key.
5. Note the pattern of iron filings that emerges on the cardboard after
tapping gently a few times. (Observation).
6. Place the compass at any point over the pattern of field. Observe the
direction of needle. (Observation 2).
Observations :
1. (a) Iron filings are arranged in the form of concentric circles.
(b) The concentric circles become larger and larger as we move away
from the wire.
(c) At the centre of loop, lines are almost straight and perpendicular to
the plane of the loop.
,Conclusion :
1. The concentric circles at every point of a current carrying circular loop
represent the magnetic field around it.
2. Magnetic field line close to the axis of loop is straight and is
perpendicular to the plane of the coil.
3. Field lines keep on diverging as we move away from the centre of loop.
2. What is meant by solenoid? How does a current carrying solenoid behave?
Give its main use.
Answer. Solenoid: A coil of many circular turns of insulated copper wire wound on a
cylindrical insulating body (i.e., cardboard etc.) such that its length is greater than its
diameter is called solenoid.
When current is flowing through the solenoid, the magnetic field line pattern
resembles exactly with those of a bar magnet with the fixed polarity,
i.e. North and South pole at its ends and it acquires the directive and attractive
properties similar to bar magnet. Hence, the current carrying solenoid behave as a
bar magnet.
Use of current carrying solenoid: It is used to form a temporary magnet called
electromagnet as well as permanent magnet.
3.For the current carrying solenoid as shown below, draw magnetic field lines
and giving reason explain that out of the three points A, B and C at which point
the field strength is maximum and at which point it is minimum.
Answer. Outside the solenoid magnetic field is minimum. At the ends of solenoid,
magnetic field strength is half to that inside it. So Minimum – at point B; Maximum –
at point A
, 4. With the help of a diagram of experimental setup describe an activity to
show that the force acting on a current carrying conductor placed in a
magnetic field increases with increase in field strength.
Answer.
Aim : To show that force acting on a current carrying conductor placed in a magnetic
field increases with the field strength.
Apparatus Required : Aluminium rod, stand horse shoe magnet of different intensity,
cell, key and connecting wires.
Procedure :
1. .Arrange the set-up as shown in figure.
2.Plug the key, the current flowing through the rod from Q to P observe
the displacement of rod.
3.Now unplug the key and remove the first horse shoe magnet and
place the second horse shoe magnet of higher magnetic field strength in
a similar manner to that of first.
4.Plug the key, the current again flow through the rod from Q to P. Again
observe the deflection of rod.
5.Now bring both’the magnet closer together (to ensure greater
magnetic field than that of previous case). Again observe the motion of
rod.
Observations : Each time, the conductor moves faster than that of previous one. It
is possible only when conductor gets accelerated more each time which required
more force. (F = ma)
Thus, if the magnetic field strength is increased, the rod will experience a greater
force and move faster.
Conclusion : The force acting on a current carrying conductor placed in a magnetic
field increases with increase in field strength.
5.What are magnetic field lines? Justify the following statements
(a) Two magnetic field lines never intersect each other.
(b) Magnetic field lines are closed curves.
Answer.
Magnetic field lines: It is defined as the path along which the unit North pole
(imaginary) tends to move in a magnetic field if free to do so.
(a) The magnetic lines of force do not intersect (or cross) one another. If they do so
then at the point of intersection, two tangents can be drawn at that point which
indicates that there will be two different directions of the same magnetic which field,
i.e. the compass needle points in two different directions which is not possible.
(b) Magnetic field lines are closed continuous curves. They diverge from the north
Important Questions Class 10 Science
Short Answer Type Questions [II] [3 Marks]
1.Describe an activity to show that the magnetic field lines produced when
current is passed through the circular coil.
Answer.
Aim : To study the characteristics of magnetic field produced by a current carrying
circular coil at its centre.
Apparatus Required : Rectangular cardboard having two holes, Thick copper
circular coils of different radii having known number of turns, key, battery, rheostat,
stand, iron filings.
Procedure :
1. Pass the coil through the two holes of cardboard in such a way that half
of the loop is above the cardboard and remaining part should be below it
and normal to the plane of cardboard.
2. Connect the circuit as shown.
3. Sprinkle iron filings uniformly on the cardboard.
4. Allow the current to pass though the coil by inserting plug in the key.
5. Note the pattern of iron filings that emerges on the cardboard after
tapping gently a few times. (Observation).
6. Place the compass at any point over the pattern of field. Observe the
direction of needle. (Observation 2).
Observations :
1. (a) Iron filings are arranged in the form of concentric circles.
(b) The concentric circles become larger and larger as we move away
from the wire.
(c) At the centre of loop, lines are almost straight and perpendicular to
the plane of the loop.
,Conclusion :
1. The concentric circles at every point of a current carrying circular loop
represent the magnetic field around it.
2. Magnetic field line close to the axis of loop is straight and is
perpendicular to the plane of the coil.
3. Field lines keep on diverging as we move away from the centre of loop.
2. What is meant by solenoid? How does a current carrying solenoid behave?
Give its main use.
Answer. Solenoid: A coil of many circular turns of insulated copper wire wound on a
cylindrical insulating body (i.e., cardboard etc.) such that its length is greater than its
diameter is called solenoid.
When current is flowing through the solenoid, the magnetic field line pattern
resembles exactly with those of a bar magnet with the fixed polarity,
i.e. North and South pole at its ends and it acquires the directive and attractive
properties similar to bar magnet. Hence, the current carrying solenoid behave as a
bar magnet.
Use of current carrying solenoid: It is used to form a temporary magnet called
electromagnet as well as permanent magnet.
3.For the current carrying solenoid as shown below, draw magnetic field lines
and giving reason explain that out of the three points A, B and C at which point
the field strength is maximum and at which point it is minimum.
Answer. Outside the solenoid magnetic field is minimum. At the ends of solenoid,
magnetic field strength is half to that inside it. So Minimum – at point B; Maximum –
at point A
, 4. With the help of a diagram of experimental setup describe an activity to
show that the force acting on a current carrying conductor placed in a
magnetic field increases with increase in field strength.
Answer.
Aim : To show that force acting on a current carrying conductor placed in a magnetic
field increases with the field strength.
Apparatus Required : Aluminium rod, stand horse shoe magnet of different intensity,
cell, key and connecting wires.
Procedure :
1. .Arrange the set-up as shown in figure.
2.Plug the key, the current flowing through the rod from Q to P observe
the displacement of rod.
3.Now unplug the key and remove the first horse shoe magnet and
place the second horse shoe magnet of higher magnetic field strength in
a similar manner to that of first.
4.Plug the key, the current again flow through the rod from Q to P. Again
observe the deflection of rod.
5.Now bring both’the magnet closer together (to ensure greater
magnetic field than that of previous case). Again observe the motion of
rod.
Observations : Each time, the conductor moves faster than that of previous one. It
is possible only when conductor gets accelerated more each time which required
more force. (F = ma)
Thus, if the magnetic field strength is increased, the rod will experience a greater
force and move faster.
Conclusion : The force acting on a current carrying conductor placed in a magnetic
field increases with increase in field strength.
5.What are magnetic field lines? Justify the following statements
(a) Two magnetic field lines never intersect each other.
(b) Magnetic field lines are closed curves.
Answer.
Magnetic field lines: It is defined as the path along which the unit North pole
(imaginary) tends to move in a magnetic field if free to do so.
(a) The magnetic lines of force do not intersect (or cross) one another. If they do so
then at the point of intersection, two tangents can be drawn at that point which
indicates that there will be two different directions of the same magnetic which field,
i.e. the compass needle points in two different directions which is not possible.
(b) Magnetic field lines are closed continuous curves. They diverge from the north
