JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Magnetic Effects of Current

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An electron is moving along the positive x -axis. If the uniform magnetic field is applied parallel to the negative z -axis. then
A. The electron will experience magnetic force along positive y -axis
B. The electron will experience magnetic force along negative y -axis
C. The electron will not experience any force in magnetic field
D. The electron will continue to move along the positive x -axis
E. The electron will move along circular path in magnetic field
Choose the correct answer from the options given below :

(A)B and E only✓ Correct
(B)A and E only
(C)C and D only
(D)B and D only

Answer: (A)

Solution

The magnetic force on the electron is

F = - e (v \times B)

. With

v

along

+ \overset{x}{^}

and

B

along

- \overset{z}{^}

v \times B = \overset{x}{^} \times (- \overset{z}{^}) = + \overset{y}{^}

. Thus

F = - e (+ \overset{y}{^}) = - \overset{y}{^}

(along negative y-axis), confirming statement B. Since the force is perpendicular to velocity, the electron moves in a circular path (statement E). Hence B and E are correct.

JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Single correct option

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JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Magnetic Effects of Current

Solution

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