Class 10 Science Chapter 12: Magnetic Effects of Electric Current MCQs with answers
10 multiple-choice questions on Magnetic Effects of Electric Current, each with its answer and the reason, written from the NCERT chapter. Open a question's solution to check your working; then take the free test to find your next chapter.
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Answer: (c) an electric current produces a magnetic effect
A compass needle is deflected near a current-carrying wire and returns when the current stops: the current produces a magnetic effect, so electricity and magnetism are related.
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Answer: (b) Oersted, in 1820
Oersted saw the compass needle deflect when a current was passed through a nearby wire, in 1820. Ampere's contribution came later and concerned the force on the conductor.
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Answer: (d) north-seeking or north pole
The end that points towards the north is the north-seeking or north pole; the other end is the south pole.
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Answer: (b) magnetic field
The region surrounding a magnet in which its force can be detected is its magnetic field. A field line is only one path drawn in that region.
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Answer: (c) east
The direction of the field at a point is the direction in which the north pole of a compass placed there points: east. West is where the south pole points.
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Answer: (a) from Y to X
Field lines emerge from the north pole and merge at the south pole outside, so X is north and Y is south. Inside the magnet they run from south to north, that is, from Y to X.
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Answer: (c) at P, because the lines are closer together there
The relative strength of the field is shown by how close the lines are: they are crowded near P and spread out near Q, so the field is stronger at P.
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Answer: (d) equal in size and opposite in direction
The field lines are concentric circles centred on the wire. P and Q lie on the same circle, at opposite ends of a diameter, so the field has the same size there but the tangents to the circle point in opposite directions.
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Answer: (c) deflects towards the west
Reversing the current reverses the direction of the field it produces, so the needle deflects the opposite way, towards the west.
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Answer: (a) adding one more cell in series to increase the current
The field at a point increases as the current increases, so an extra cell gives a larger deflection. Lifting the compass moves it farther from the wire, where the field is smaller; removing a cell lowers the current; reversing the battery only reverses the direction.