1.Why does a compass needle get deflected when brought near a bar magnet?
A compass needle is a small bar magnet. When it is brought near a bar magnet, its magnetic field lines interact with that of the bar magnet. Hence, a compass needle shows a deflection when brought near the bar magnet.
2.List the properties of magnetic lines of force.
The properties of magnetic lines of force are as follows.
(a) Magnetic field lines emerge from the north pole.
(b) They merge at the south pole.
(c) The direction of field lines inside the magnet is from the south pole to the north pole.
(d) Magnetic lines do not intersect with each other.
3.Why don’t two magnetic lines of force intersect each other?
If two field lines of a magnet intersect, then at the point of intersection, the compass needle points in two different directions. This is not possible. Hence, two field lines do not intersect each other.
4.State Fleming’s left-hand rule.
Fleming’s left hand rule states that if we arrange the thumb, the centre finger, and the forefinger of the left hand at right angles to each other, then the thumb points towards the direction of the magnetic force, the centre finger gives the direction of current, and the forefinger points in the direction of magnetic field.
5. What is the principle of an electric motor?
The working principle of an electric motor is based on the magnetic effect of current. A current-carrying loop experiences a force and rotates when placed in a magnetic field. The direction of rotation of the loop is given by the Fleming’s left-hand rule.
6.What is the role of the split ring in an electric motor?
The split ring in the electric motor acts as a commutator. The commutator reverses the direction of current flowing through the coil after each half rotation of the coil. Due to this reversal of the current, the coil continues to rotate in the same direction.
7.Explain different ways to induce current in a coil.
The different ways to induce current in a coil are as follows:
(a) If a coil is moved rapidly between the two poles of a horse-shoe magnet, then an electric current is induced in the coil.
(b) If a magnet is moved relative to a coil, then an electric current is induced in the coil.
8. What are the essential difference between an AC generator and a DC generator
The essential difference between an AC generator and a DC generator is that
(a) AC generator has an electromagnet while a DC generator has permanent magnet.
(b) DC generator will generate a higher voltage. AC generator will not generate a higher voltage
A compass needle is a small bar magnet. When it is brought near a bar magnet, its magnetic field lines interact with that of the bar magnet. Hence, a compass needle shows a deflection when brought near the bar magnet.
2.List the properties of magnetic lines of force.
The properties of magnetic lines of force are as follows.
(a) Magnetic field lines emerge from the north pole.
(b) They merge at the south pole.
(c) The direction of field lines inside the magnet is from the south pole to the north pole.
(d) Magnetic lines do not intersect with each other.
3.Why don’t two magnetic lines of force intersect each other?
If two field lines of a magnet intersect, then at the point of intersection, the compass needle points in two different directions. This is not possible. Hence, two field lines do not intersect each other.
4.State Fleming’s left-hand rule.
Fleming’s left hand rule states that if we arrange the thumb, the centre finger, and the forefinger of the left hand at right angles to each other, then the thumb points towards the direction of the magnetic force, the centre finger gives the direction of current, and the forefinger points in the direction of magnetic field.
5. What is the principle of an electric motor?
The working principle of an electric motor is based on the magnetic effect of current. A current-carrying loop experiences a force and rotates when placed in a magnetic field. The direction of rotation of the loop is given by the Fleming’s left-hand rule.
6.What is the role of the split ring in an electric motor?
The split ring in the electric motor acts as a commutator. The commutator reverses the direction of current flowing through the coil after each half rotation of the coil. Due to this reversal of the current, the coil continues to rotate in the same direction.
7.Explain different ways to induce current in a coil.
The different ways to induce current in a coil are as follows:
(a) If a coil is moved rapidly between the two poles of a horse-shoe magnet, then an electric current is induced in the coil.
(b) If a magnet is moved relative to a coil, then an electric current is induced in the coil.
8. What are the essential difference between an AC generator and a DC generator
The essential difference between an AC generator and a DC generator is that
(a) AC generator has an electromagnet while a DC generator has permanent magnet.
(b) DC generator will generate a higher voltage. AC generator will not generate a higher voltage
(c) An AC generator has two rings called slip rings. A DC generator has two half rings called commutator.
Q.2 If the frequency of A.C. is 50 Hz. Then how many times it is changing its direction in 1 second?
Ans- 100 Times.
Q.3 What is the pattern of the magnetic field lines around a straight conductor carrying current?
Ans. Concentric circles
(d) AC generator has slip rings while the DC generator has a commutator.
9. 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?
A current induces in a solenoid if a bar magnet is moved relative to it. This is the principle of electromagnetic induction.
(i) When a bar magnet is pushed into a coil of insulated copper wire, a current is induced momentarily in the coil. As a result, the needle of the galvanometer deflects momentarily in a particular direction.
(ii) When the bar magnet is withdrawn from inside the coil of the insulated copper wire, a current is again induced momentarily in the coil in the opposite direction. As a result, the needle of the galvanometer deflects momentarily in the opposite direction.
(iii) When a bar magnet is held stationary inside the coil, no current will be induced in the coil. Hence, galvanometer will show no deflection.1o. If we place a compass needle near straight conductor carrying current
10. (a)What happens to the deflection of the compass needle if the direction of current is reversed .
(b)What change will you notice in the compass needle if it is moved away from conductor but the current through the conductor remains the same?
(a) Direction of deflection will reverse
(b) Deflection will decrease
(i) When a bar magnet is pushed into a coil of insulated copper wire, a current is induced momentarily in the coil. As a result, the needle of the galvanometer deflects momentarily in a particular direction.
(ii) When the bar magnet is withdrawn from inside the coil of the insulated copper wire, a current is again induced momentarily in the coil in the opposite direction. As a result, the needle of the galvanometer deflects momentarily in the opposite direction.
(iii) When a bar magnet is held stationary inside the coil, no current will be induced in the coil. Hence, galvanometer will show no deflection.1o. If we place a compass needle near straight conductor carrying current
10. (a)What happens to the deflection of the compass needle if the direction of current is reversed .
(b)What change will you notice in the compass needle if it is moved away from conductor but the current through the conductor remains the same?
(a) Direction of deflection will reverse
(b) Deflection will decrease
(One Mark Question)
Q.1 Why does the bulk of iron fillings stick to the ends of a bar magnet and not at its centre?Ans. Because at the ends magnetic strength is maximum and at centres magnetic strength is least.Q.2 If the frequency of A.C. is 50 Hz. Then how many times it is changing its direction in 1 second?
Ans- 100 Times.
Q.3 What is the pattern of the magnetic field lines around a straight conductor carrying current?
Ans. Concentric circles
Q.4 If the current is flowing in the direction of advancemet of screw, then what is the direction of magnetic field lines?
Ans.In the direction of rotation of screw.
Q.5 How can you say that the magnetic field is uniform inside the solenoid.
Ans. Because field lines are parallel inside the solenoid.
Q.6 Which property of a proton will change while it moves freely in a magnetic field?
Ans. Momentum or Velocity.
Q.7 According to Flemings right hand rule, which part of right hand indicate the movement of conductor?
Ans. Thumb
Q.8 If the no. of turns of a circular current carrying coil are doubled, then how will the magnetic field produced by it changes?
Ans. Doubled
Q.9 In which position the force on conductor is maximum when it is placed in uniform magnetic field?
Ans. When conductor is Perpendicular to field
10 A current through a horizontal power line flows in north to south direction.What is the direction of magnetic field (i)at a point directly below it and (ii)at a point directly above it?Ans. (i) West to East (ii) East to West
Ans.In the direction of rotation of screw.
Q.5 How can you say that the magnetic field is uniform inside the solenoid.
Ans. Because field lines are parallel inside the solenoid.
Q.6 Which property of a proton will change while it moves freely in a magnetic field?
Ans. Momentum or Velocity.
Q.7 According to Flemings right hand rule, which part of right hand indicate the movement of conductor?
Ans. Thumb
Q.8 If the no. of turns of a circular current carrying coil are doubled, then how will the magnetic field produced by it changes?
Ans. Doubled
Q.9 In which position the force on conductor is maximum when it is placed in uniform magnetic field?
Ans. When conductor is Perpendicular to field
10 A current through a horizontal power line flows in north to south direction.What is the direction of magnetic field (i)at a point directly below it and (ii)at a point directly above it?Ans. (i) West to East (ii) East to West
thnx.........nd cbse cce z suckin~!!!!!!!!!!
ReplyDeleteA helpful guide for students as same as the students need thanks for shearing CBSE NCERT Solutions
ReplyDelete