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JEE PHYSICS MCQ: MAGNETIC EFFECT OF CURRENT
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Medium
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Understanding
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Assertion: Free electron always keep on moving in a conductor even then no magnetic force act on them in magnetic field unless a current is passed through it.
Reason: The average velocity of free electron is zero.
Reason: The average velocity of free electron is zero.
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Correct option: A
(A) and (R) are true and (R) is the correct explanation of (A)
Option A ((A) and (R) are true and (R) is the correct explanation of (A)) is correct because free electrons are always in motion, but their average velocity is zero, resulting in no net magnetic force unless a current is present.
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A needle made of bismuth is suspended freely in a magnetic field. The angle which the needle makes with the magnetic field is:
Assertion: If a charged particles is moving in perpendicular uniform magnetic field, its kinetic energy does not change
Reason: Velocity of charge particle is not changing in magnetic field. Pick out the wrong statement : A steady current is flowing in a circular coil of radius , made up of a thin conducting wire. The magnetic field at the center of the loop is . Now, a circular loop of radius is made from the same wire without changing its length, by unfolding and refolding the loop, and the same current is passed through it. If new magnetic field at the center of the coil is , then the ratio is Lorentz force can be calculated by using the formula Two particles and having equal charges, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describe circular path of radius and respectively. The ratio of mass of to that of is :
Reason: Velocity of charge particle is not changing in magnetic field. Pick out the wrong statement : A steady current is flowing in a circular coil of radius , made up of a thin conducting wire. The magnetic field at the center of the loop is . Now, a circular loop of radius is made from the same wire without changing its length, by unfolding and refolding the loop, and the same current is passed through it. If new magnetic field at the center of the coil is , then the ratio is Lorentz force can be calculated by using the formula Two particles and having equal charges, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describe circular path of radius and respectively. The ratio of mass of to that of is :