CBSE Class 10 Science Chapter-13 Magnetic Effects of Electric Current – Free PDF Download
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CBSE Class 10 Science Chapter-13 Magnetic Effects of Electric Current Important Questions
CBSE Class 10 science Important Questions Chapter 13 – Magnetic Effects of Electric Current
2 Mark Questions
1. State two properties of magnetic lines of force?
Ans. (i) Magnetic lines of force are closed continuous curves.
(ii)The tangent at any point on the magnetic line of force which gives the direction of magnetic field at that point.
2. Why does a compass needle deflected when brought near a bar magnet?
Ans. Compass needle experience a force is the magnetic field of a bar magnet due to which it deflects.
3. The magnetic field lines in a given region is uniform. Draw a diagram to represent.
Ans.
4. Write two ways to induce current in a coil?
Ans. (i) By moving a bar magnet toward or away from the coil.
(ii) By placing a coil near another coil connected across a battery.
5. Draw magnetic field lines around a bar magnet? Give one point of difference between uniform and non- uniform magnetic field.
Ans. The space or region where field is same everywhere is known as Uniform magnetic field. The magnetic field which is unequal in magnitude and direction at every point in the space is called non- uniform magnetic field.
6. Why do not two magnetic field lines intersect each other?
Ans. The two magnetic field lines never intersect each other because at the point of intersection there will be two directions of magnetic field, which is not possible.
7. Name and state rule used to determine the direction of magnetic field produced around a straight conductor carrying current?
Ans. The rule is known as right hand thumb rule if a current carrying conductor is held in our right hand such that thumb points in the direction of current, then the curled fingers of the hand indicate the direction of magnetic field.
8. What is electric fuse? Where it is connected in a circuit?
Ans. An electric fuse is a safety device which is made up of a wire made of copper or aluminum or a tin lead alloy. An electric fuse must be connected in the path of the circuit so that overloading which can cause fire due to short circuit can be avoided.
9. State the factors on which strength of magnetic field at a point due to a current carrying conductor depends?
Ans. The factors on which strength of a magnetic field at a point depends.
(1) Amount of current (I) flowing through the conductor
(2) Distance (r) from the current carrying conductor.
10. What is an electromagnet? Write two uses of an electromagnet?
Ans. When current is passed through a solenoid it behaves as a magnet and is called as an electromagnet.
The two uses of an electromagnet are-
(1) They are used to lift heavy iron pieces.
(2) They are used in many devices like micro phone, radio sets, electric bell etc.
11. State and define S.I unit of magnetic field?
Ans. The S.I unit of magnetic field is Tesla (T). The magnetic field strength is said to be one Tesla if 1meter long conductor carrying 1 ampere current experiences 1 Newton force, when placed perpendicular to the direction of magnetic field.
12. A current carrying conductor is placed perpendicular to the uniform magnetic field. What happens to displacement of the conductor if
(i) strength of current increases
(ii) If horse shoe magnet is replaced by a weak horse shoe magnet.
Ans. The displacement of the conductor
(i)will increase on increasing the current
(ii)Will decrease on using a weak horse shoe magnet.
13. Draw magnetic field around a bar magnet.
Ans. Magnetic field lines are as follows:
14. Why don’t two magnetic lines of force intersect each other?
Ans. No, two magnetic field lines can ever intersect each other. If they do, then it would mean that at the point of intersection there are two directions of magnetic field, which is not possible.
15. 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. As per right-hand rule, we find that inside the loop, the magnetic field lines are directed perpendicular to the plane of paper in the inward direction. Outside the loop magnetic field lines are directed out of the plane paper.
16. The magnetic field in a given region is uniform. Draw a diagram to represent it.
Ans.The uniform magnetic field is represented by parallel equispaced lines of equal length as follows:
17. What is the role of the split ring in an electric motor?
Ans. In electric motor, the split ring acts as commutator. Due to its action, the direction of current flowing in motor coil reverses after half turn, giving rise to a continuous rotation of the coil and the axle.
18. State the principle of an electric generator.
Ans. An electric generator is based on the principle of electromagnetic induction. When a rectangular coil is rotated in a uniform magnetic field, an induced emf is generated between the ends of the coil.
19. Which sources produce alternating current?
Ans. A.C. generator and common inverter used in houses for emergency power supply produce alternating current.
20. Name two safety measures commonly used in electric circuits and appliances.
Ans. Two safety measures are:
(a) use of earth wire and proper earthing.
(b) use of fuse.
21. State whether the following statements are true or false.
(a) An electric motor converts mechanical energy into electrical energy.
(b) An electric generator works on the principle of electromagnetic induction.
(c) The field at the centre of a long circular coil carrying current will be parallel straight line
(d) A wire with green insulation is usually the live wire of an electric supply.
Ans. (a) False
(b) True
(c) True
(d) False
22. When is the force experienced by a current-carrying conductor placed in magnetic field largest?
Ans. The force experienced by a current carrying conductor placed in a magnetic field is largest when the conductor is placed with its length in a direction perpendicular to that of magnetic field.
23. Name some devices in which electric motors are used.
Ans. Electric motors are used in all devices where we want to convert electrical energy into Mechanical energy. In our houses, electric motors, coolers, mixer grinders, washing machines, computers etc motor is used.
24.When does an electric short circuit occurs?
Ans. If either the insulation of wires used in an electric circuit is damaged or there is a fault in the appliances, live wire and neutral wire may come in direct contact. As a result, the current in the circuit abruptly rises and short circuiting occurs.
25. Why is the earth pin thicker and longer than the live and the neutral pins?
Ans. it is thicker so that it does not enter into the live or neutral sockets. It is made longer so that it gets connected to the earth terminal earlier than the live and neutral pins. This ensures the safety of the user.
26. A current-carrying straight conductor is placed in the east-west direction. What will be the direction of the force experienced by this conductor due to earth’s magnetic field? How will this force get affected on? (a) reversing the direction of floe of floe of current (b) doubling the magnitude of current.
Ans. The direction of earth’s magnetic field is from U-south to 0-north. Let current is from west to east. Therefore, force is vertically upwards.
(a) By reversing the direction of current, the direction of will be reversed i.e. vertically downwards.
(b) The magnitude of the force is doubled.
27. Give two uses of electromagnets.
Ans. (i) It is used in cranes for lifting heavy loads.
(ii) used in electric bells.
28. A straight wire carrying electric current is moving out of plane of paper and is perpendicular to it. What is the direction and type of induced magnetic field?
Ans. Induced magnetic field will be in the form of concentric circles in the plane of paper.
29. Why does the bulk of iron fillings slick to the ends of a bar magnet and not at its centre?
Ans. Because at the ends magnetic strength is maximum and at canters magnetic strength is least.
30. A student draws three magnetic field lines 1,2 and 3 of a bar magnet with the help of a compass needle as shown in figure.
(a) Is this configuration possible?
(b) If not what is
Ans. (a)No wrong in figure and why?
(b) (i) Two field lines cannot intersect (ii) direction of field lines ‘3’ is wrong.
31. Suppose you are sifting in a room facing one of the wall. An electron beam and is moving horizontally from your back goes towards the wall in front you deflected to our left, what is the direction of magnetic field in the room?
Ans. Vertically upward.
32. A current through a horizontal power line flows in north to south direction. What is the direction of magnetic directly above it? field (i)at a point directly below it and (ii)at a point
Ans. (i) West to East (ii) East to West
33. Electric appliances like electric -press, toaster, fans etc are connected to electric mains through three-pin plug. Why?
Ans. Electric appliances are connected to three pin plug because heavy appliances require earth wire, so that in case of leakage of any current it goes to earth and user will not get shock