Question

In a current carrying solenoid the current is flowing clockwise from left

end. Draw the magnetic field produced in it.​

Answer 1

Answer:

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

Ans. A compass needle is a small bar magnet with north and south pole. The compass needle deflects due to repulsion/attraction with the bar magnet.

3.  List the properties of magnetic lines of force.

Ans. Properties of magnetic field lines of force:

      (i) Magnetic field lines travel from N-pole of magnet towards 5-pole, outside the magnet and from S-pole to N-pole inside the magnet.

      (ii) The strength of magnet/magnetic field is given by how close the field lines are if the field lines are closer magnet is stronger.

      (iii) No two magnetic field lines ever intersect each other.

4.  Why don’t two magnetic lines of force intersect each other?

Ans. The magnetic field lines never intersect each other as an intersection of the field lines means the magnetic field at that point has two directions, which is not possible because the resultant force on a pole (north/south) at any point can only be in one direction.

5.  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.

Ans.



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

Ans.



           The magnetic field in a given region is uniform can be represented by showing parallel lines at equidistance.

7.  Choose the correct option.

           The magnetic Meld inside a long straight solenoid-carrying current

           (a) is zero.

(b) decreases as we move towards its end.

           (c) increases as we move towards its end.

(d) is the same at all points.

Ans. (d) is the same at all points.

8.  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

Ans. Velocity and momentum

9.  In activity 13.7 (on page 234) 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.

Ans. (i) If current in rod AB is increased its displacement will increase.

           (ii) If a stronger horse-shoe magnet is used then the displacement of rod AB will increase.

           (iii) If the length of the rod AB is increased force acting on it will increase and the displacement of the rod also increases.

10.  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

           Ans. (c) downward

11.  State Fleming’s left hand rule.

Ans. According to this rule, stretch the thumb, fore-finger and middle finger of left hand such that they are mutually perpendicular. If the middle finger points in the direction of the magnetic field, the fore-finger points in the direction of flow of current, then the thumb points in the direction of motion i.e., force acting on the conductor.



12.  What is the principle of an electric motor?

Ans. The principle of an electric motor is based on Fleming’s left hand rule. i.e., a current carrying conductor experiences a force when placed in a magnetic field.

13.  What is the role of the split ring in on electric motor?

Ans. In an electric motor split ring acts as a commutator. Split ring is connected to the ends of the coil and the direction of current flowing in motor coil reverses after every half turn. Which results in the continuous rotation of the coil and the ends.

14.  Explain different ways to induce current in a coil.

Ans. We can induce current in a coil

           (i) by moving a coil in a magnetic field or by changing the magnetic field around it.

           (ii) By increasing the number of coils the induced current value can be increased.

15.  State the principle of an electric generator:

Ans. In an electric generator mechanical energy is used to rotate a conductor in a magnetic field to produce electricity.

           Fleming’s right hand rule is used where motion and magnetic field is given and the current is induced.

16.  Name some sources of direct current.

Ans. Dynamo and battery cells.

17.  Which sources produce alternating current?

Ans. Dynamo or generators with split ring type commutator.

18.  Choose the correct option.

           A rectangular coil of copper wire is rotated in magnetic field. The direction of the induced current changes ones in each

           (a) two revolutions                      (b) one revolution

           (c) half revolution                        (d) one-fourth revolution

Ans. (c) half revolution

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

Ans. (i) Use earthing wiring for metallic body electrical appliances. (ii) Use miniature circuit breakers, (MCB) i.e., fuse

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