CBSE Class 10 Science Magnetic Effects of Electric Current Worksheet Set 12

This printable Class 10 Science worksheet on Magnetic Effects of Electric Current has 25 short questions with answers on force on conductors, solenoid poles, electromagnetic induction and generators. It mixes fill-in-the-blanks, true or false statements and very short answers, with no diagrams so that it prints cleanly.

Fill in the Blanks

Question 1. The force between currents is called the ______ force.
Answer:
magnetic force.
In simple words: Currents exert magnetic force on each other.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 2. The N-pole of a compass points to the ______ pole of a permanent magnet.
Answer:
south pole, because unlike poles attract.
In simple words: Unlike poles attract.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 3. The force that a magnetic field exerts on a current is always perpendicular to the ______ and to the ______.
Answer:
The field and the current.
In simple words: Force is at right angles to both field and current.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 4. In a magnetic field pointing away from you, an electron travelling to the right will experience a force in the ______ direction.
Answer:
downward. The electron moving to the right is a current to the left; with the field pointing away from you, Fleming's left-hand rule gives a force downwards.
In simple words: Use the left-hand rule with the current opposite to the electron's motion.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 5. Magnetic fields are produced by ______.
Answer:
currents (moving charges) and magnets.
In simple words: Moving charges make magnetic fields.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 6. You are looking into a solenoid, at its S-pole, along its axis. From your viewpoint, the direction of the current in the solenoid is ______.
Answer:
clockwise (clock-face rule: clockwise is a south pole).
In simple words: Clockwise face is a south pole.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 7. Crowding the wires of a solenoid more closely together will ______ the strength of the field inside it.
Answer:
increase the strength.
In simple words: More turns per unit length give a stronger field.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 8. Magnetic field lines emerge from the ______ pole of a solenoid or a permanent magnet.
Answer:
north pole.
In simple words: Lines emerge from the north pole.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 9. You are looking down the axis of a solenoid, and the current from your position is clockwise. The end of the solenoid facing you is a ______ pole.
Answer:
south pole.
In simple words: Clockwise means south.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 10. A generator converts mechanical energy into ______ energy. It works on the basis of ______.
Answer:
electrical energy; electromagnetic induction.
In simple words: A generator uses induction to make electricity.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 11. In our houses we receive AC electric power of ______ with a frequency of ______.
Answer:
220 V with a frequency of 50 Hz.
In simple words: Mains supply is 220 V, 50 Hz.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 12. The armature in a motor rotates within a(n) ______ field.
Answer:
magnetic field.
In simple words: The armature turns in a magnetic field.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 13. To produce DC, the output of a generator must be fed through a(n) ______.
Answer:
commutator (split ring).
In simple words: A commutator changes AC output to DC.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

Question 14. In any generator, the current in the armature is of the ______ type.
Answer:
A.C. (alternating) type.
In simple words: The armature always produces AC.

Teacher's Note:
1. Write only the missing word or phrase.
2. Learn this fact for quick recall.

True or False (Give the Correct Statement if False)

Question 15. The direction of force on a current carrying conductor placed in a magnetic field cannot be reversed by reversing the direction of magnetic field.
Answer:
False. Reversing the direction of the magnetic field also reverses the force.
In simple words: Reversing the field also reverses the force.

Teacher's Note:
1. Give the correct statement for any false answer.
2. Think of the underlying rule before answering.

Question 16. Two magnetic lines of force never intersect each other.
Answer:
True. At a point of intersection the field would have two directions, which is impossible.
In simple words: Field lines never cross.

Teacher's Note:
1. Give the correct statement for any false answer.
2. Think of the underlying rule before answering.

Question 17. The field lines inside the infinite solenoid are in the form of parallel straight lines.
Answer:
True. The field inside a solenoid is uniform.
In simple words: Parallel lines mean uniform field.

Teacher's Note:
1. Give the correct statement for any false answer.
2. Think of the underlying rule before answering.

Question 18. An electric generator works on the principle of electromagnetic induction.
Answer:
True.
In simple words: Generators use electromagnetic induction.

Teacher's Note:
1. Give the correct statement for any false answer.
2. Think of the underlying rule before answering.

Question 19. In a DC electric motor a pair of split rings is used as commutator.
Answer:
True. The split rings reverse the current in the coil every half rotation.
In simple words: Split rings act as the commutator.

Teacher's Note:
1. Give the correct statement for any false answer.
2. Think of the underlying rule before answering.

Question 20. The magnitude of induced current can be increased by decreasing the speed of rotation of coil.
Answer:
False. Increasing the speed of rotation increases the induced current.
In simple words: Faster rotation gives a larger induced current.

Teacher's Note:
1. Give the correct statement for any false answer.
2. Think of the underlying rule before answering.

Question 21. The magnitude of induced current can be decreased by increasing the area of cross section of coil.
Answer:
False. A larger area of the coil gives a larger induced current.
In simple words: A larger coil area gives a larger induced current.

Teacher's Note:
1. Give the correct statement for any false answer.
2. Think of the underlying rule before answering.

Very Short Answer Questions

Question 22. An alternating electric current has a frequency of 50 Hz. How many times does it change its direction in one second?
Answer:
Each cycle contains two reversals, so the current changes direction 2 × 50 = 100 times in one second.
In simple words: 50 Hz gives 100 reversals per second.

Teacher's Note:
1. Remember two reversals per cycle.
2. Show the multiplication.

Question 23. What is the direction of magnetic field at the centre of a coil carrying current in (i) clockwise (ii) anticlockwise direction?
Answer:
(i) For a clockwise current, the field at the centre is along the axis of the coil, inwards (away from the viewer).
(ii) For an anticlockwise current, it is along the axis, outwards (towards the viewer).
In simple words: Clockwise gives field into the coil, anticlockwise gives it out.

Teacher's Note:
1. Use the right-hand thumb rule on the loop.
2. Clockwise face is a south pole.

Question 24. How will the direction of force be changed, if the current is reversed in the conductor placed in a magnetic field?
Answer:
The direction of force is also reversed.
In simple words: Reverse the current, reverse the force.

Teacher's Note:
1. Use Fleming's left-hand rule.
2. Reversing both field and current restores the force.

Question 25. Name the rule used to find the direction of force on a current carrying conductor.
Answer:
Fleming's left-hand rule.
In simple words: Left hand gives the force on a conductor.

Teacher's Note:
1. Mention the three fingers.
2. Do not mix with the right-hand rule.