NCERT Class X Science Class: Chapter –13. Magnetic Effects of Electric Current – Part-2

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Question 5:

A uniform magnetic field exists in the plane of paper pointing from left to right as shown in Figure. In the field an electron and a proton move as shown. The electron and the proton experience

(a) Forces both pointing into the plane of paper

(b) Forces both pointing out of the plane of paper

(c) Forces pointing into the plane of paper and out of the plane of paper, respectively

(d) Force pointing opposite and along the direction of the uniform magnetic field respectively

Image Uniform Magnetic Field

Image Uniform Magnetic Field

Image Uniform Magnetic Field

Answer: A

Question 6:

Commercial electric motors do not use

(a) An electromagnet to rotate the armature

(b) Effectively large number of turns of conducting wire in the current carrying coil

(c) A permanent magnet to rotate the armature

(d) A soft iron core on which the coil is wound

Answer: C

Image Permanent magnet to rotate the armature

Image Permanent Magnet to Rotate the Armature

Image Permanent magnet to rotate the armature

Question 7:

In the arrangement shown in Figure there are two coils wound on a non-conducting cylindrical rod. Initially the key is not inserted. Then the key is inserted and later removed. Then

Image Two coils wound on a non-conducting cylindrical rod

Image Two Coils Wound on a Non-Conducting Cylindrical Rod

Image Two coils wound on a non-conducting cylindrical rod

(a) The deflection in the galvanometer remains zero throughout

(b) There is a momentary deflection in the galvanometer but it dies out shortly and there is no effect when the key is removed

(c) There are momentary galvanometer deflections that die out shortly; the deflections are in the same direction

(d) There are momentary galvanometer deflections that die outshortly; the deflections are in opposite directions

Answer: D

Question 8:

Choose the incorrect statement

(a) Fleming’s right-hand rule is a simple rule to know the direction of induced current

(b) The right-hand thumb rule is used to find the direction of magnetic fields due to current carrying conductors

(c) The difference between the direct and alternating currents is that the direct current always flows in one direction, whereas the alternating current reverses its direction periodically

(d) In India, the AC changes direction after every

Answer: D

AC frequency in India is . The direction changes twice ineach cycle so that change of direction takes place after every .

Image Sine Wave and Amplitude

Image Sine Wave and Amplitude

Image Sine Wave and Amplitude