A particle (mass = m and charge = q ) is moving in a region in which there exists a uniform electric field E i ^ and a uniform magnetic field B k ^ . At t = 0 , the particle is at 0 , a and is moving with v i ^ . After some time, the particle is located at 2 a , 0 and has a velocity − 2 v j ^ , then which of the following is true?

By work energy theorem W mag + W ele = 1 2 m ( 2 v ) 2 - 1 2 m ( v ) 2 0 + qE 0 2 a = 3 2 mv 2 E 0 = 3 4 mv 2 qa Rate of work done at initial instant = power of electric force = qE 0 V = 3 4 mv 3 a

Physics - Magnetism Question with Solution | TestHub

PhysicsMagnetismMiscellaneousHard2 minPYQ_2020

PhysicsHardsingle choice

A particle (mass = $m$ and charge = $q$ ) is moving in a region in which there exists a uniform electric field $E \hat{i}$ and a uniform magnetic field $B \hat{k}$ . At $t = 0$ , the particle is at $(0, a)$ and is moving with $v \hat{i}$ . After some time, the particle is located at $(2 a, 0)$ and has a velocity $- 2 v \hat{j}$ , then which of the following is true?

Options:

Answer:

Solution:

By work energy theorem

$W_{mag} + W_{ele} = \frac{1}{2} m (2 v)^{2} - \frac{1}{2} m (v)^{2}$

$0 + {qE}_{0} 2 a = \frac{3}{2} {mv}^{2}$
$E_{0} = \frac{3}{4} \frac{{mv}^{2}}{qa}$

Rate of work done at initial instant $=$ power of electric force

$= {qE}_{0} V$
$= \frac{3}{4} \frac{{mv}^{3}}{a}$

Stream:JEESubject:PhysicsTopic:MagnetismSubtopic:Miscellaneous

⏱ 2mℹ️ Source: PYQ_2020

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