JEE Advanced 2008 Physics - Class 12 JEEAdv08Phc751 Solution: A particle of mass m and charge q, moving with velocity v…

QJEEAdv08Phc751: JEE Advanced 2008 Physics - Class 12 JEEAdv08Phc751 Solution: A particle of mass m and charge q, moving with velocity v…

A particle of mass m and charge q, moving with velocity v enters Region II normal to the boundary as shown in the figure. Region II has a uniform magnetic field B perpendicular to the plane of the paper. The length of the Region II is $l$ . Choose the correct choice (s).

IIT-JEE 2008 Paper 1 Offline Physics - Magnetism Question 7 English

Multiple Choice Options

A The particle enters Region III only if its velocity v>qlBm
B The particle enters Region III only if its velocity v
C Path length of the particle in Region II is maximum when velocity v=qlBm
D Time spent in Region II is same for any velocity v as long as the particle returns to Region I

Step-by-Step Verified Solution

IIT-JEE 2008 Paper 1 Offline Physics - Magnetism Question 7 English Explanation

As the particle enters the magnetic field, a force acts on it due to the magnetic field which moves the particle in a circular path of radius.

$r = \frac{m v}{q B}$

For the particle entering in region III, r > $l$

$\Rightarrow \frac{m v}{q B} > l$

$\Rightarrow v > q l B / m$

For maximum path length in region II, r = $l$

$∴$ $l = \frac{m v}{q B}$

$\Rightarrow v = \frac{q l B}{m}$

[ $∵$ $v_{max} = \frac{q B l}{m}, T = \frac{2 π r}{v} = \frac{2 π m}{q . B}$ ]

The time taken by the particle to move in region II before coming back in region I is given by $t = π m$ , which is independent of v.

QJEEAdv08Phc751: JEE Advanced 2008 Physics - Class 12 JEEAdv08Phc751 Solution: A particle of mass m and charge q, moving with velocity v…

Multiple Choice Options

Step-by-Step Verified Solution

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