JEE Main 2022 (Online) 25th June Morning Shift | Magnetic Effect of Current Question 80 | Physics

A long straight wire with a circular cross-section having radius R, is carrying a steady current I. The current I is uniformly distributed across this cross-section. Then the variation of magnetic field due to current I with distance r (r < R) from its centre will be :

B $$\propto$$ r²

B $$\propto$$ r

B $$\propto$$ $${1 \over {{r^2}}}$$

B $$\propto$$ $${1 \over {{r}}}$$

JEE Main 2022 (Online) 24th June Evening Shift

MCQ (Single Correct Answer)

-1

A proton, a deutron and an $$\alpha$$-particle with same kinetic energy enter into a uniform magnetic field at right angle to magnetic field. The ratio of the radii of their respective circular paths is :

1 : $$\sqrt 2 $$ : $$\sqrt 2 $$

1 : 1 : $$\sqrt 2 $$

$$\sqrt 2 $$ : 1 : 1

1 : $$\sqrt 2 $$ : 1

JEE Main 2022 (Online) 24th June Morning Shift

MCQ (Single Correct Answer)

-1

Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : In an uniform magnetic field, speed and energy remains the same for a moving charged particle.

Reason (R) : Moving charged particle experiences magnetic force perpendicular to its direction of motion.

Both (A) and (R) are true and (R) is the correct explanation of (A).

Both (A) and (R) are true but (R) is NOT the correct explanation of (A).

(A) is true but (R) is false.

(A) is false but (R) is true.

JEE Main 2022 (Online) 24th June Morning Shift

MCQ (Single Correct Answer)

-1

The magnetic field at the centre of a circular coil of radius r, due to current I flowing through it, is B. The magnetic field at a point along the axis at a distance $${r \over 2}$$ from the centre is :

B/2

$${\left( {{2 \over {\sqrt 5 }}} \right)^3}B$$

$${\left( {{2 \over {\sqrt 3}}} \right)^3}B$$

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