WB JEE 2020 | Magnetism Question 14 | Physics

WB JEE 2020

MCQ (Single Correct Answer)

-0.25

WB JEE 2020 Physics - Magnetism Question 31 English

As shown in the figure, a single conducting wire is bent to form a loop in the form of a circle of radius r concentrically inside a square of side a, where a : r = 8 : $$\pi $$. A battery B drives a current through the wire. If the battery B and the gap G are of negligible sizes, determine the strength of magnetic field at the common centre O.

$${{{\mu _0}I} \over {2\pi a}}\sqrt 2 (\sqrt 2 - 1)$$

$${{{\mu _0}I} \over {2\pi a}} (\sqrt 2 + 1)$$

$${{{\mu _0}I} \over {\pi a}}2\sqrt 2 (\sqrt 2 + 1)$$

$${{{\mu _0}I} \over {\pi a}}2\sqrt 2 (\sqrt 2 $$ - $$ 1)$$

WB JEE 2020

MCQ (Single Correct Answer)

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WB JEE 2020 Physics - Magnetism Question 32 English

As shown in the figure, a wire is bent to form a D-shaped closed loop, carrying current I, where the curved part is a semi-circle of radius R. The loop is placed in a uniform magnetic field B, which is directed into the plane of the paper. The magnetic force felt by the closed loop is

zero

IRB

2IRB

$${1 \over 2}$$ IRB

WB JEE 2019

MCQ (Single Correct Answer)

-0.25

To which of the following quantities, the radius of the circular path of a charged particle moving at right angles to a uniform magnetic field is directly proportional?

energy of the particle

magnetic field

charge of the particle

momentum of the particle

WB JEE 2019

MCQ (Single Correct Answer)

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An electric current 'I' enters and leaves a uniform circular wire of radius r through diametrically opposite points. A particle carrying a charge q moves along the axis of the circular wire with speed v. What is the magnetic force experienced by the particle when it passes through the centre of the circle?

$$qv{{{\mu _0}i} \over a}$$

$$qv{{{\mu _0}i} \over {2a}}$$

$$qv{{{\mu _0}i} \over {2\pi a}}$$

Zero

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