SATHEE: moving-charges-and-magnetism Question 29

moving-charges-and-magnetism Question 29

Question: Q. 1. (i) Write an expression for the force $\vec{F}$ acting on a particle of mass $m$ and charge $q$ moving with velocity $\vec{v}$ in a magnetic field $\vec{B}$ . Under what conditions will it move in (a) a circular path and (b) a helical path?

(ii) Show that kinetic energy of the particle moving in magnetic field remains constant.

U] [Delhi III 2017]

Show Answer

Solution:

Ans. (i) Expression for force acting on charged particle 1

(a) Condition for circular path

(b) Condition for helical path

(ii) Showing Kinetic energy is constant

(i) $\vec{F} = q (\vec{v} \times \vec{B})$

(a) When velocity of charge particle and magnetic field are perpendicular to each othe

(b) When velocity is neither parallel norperpendicular to the magnetic field.

$1 / 2$

(ii) The force, experienced by the charged particle, is perpendicular to the instantaneous velocity $\vec{v}$ , at all instants. Hence the magnetic force cannot bring any change in the speed of the charged particle. Since speed remains constant, the kinetic energy also stays constant.

[CBSE Marking Scheme 2017]

[II Q. 2. State the Lorentz’s force and express it in vector form. Which pair of vectors are always perpendicular to each other? Derive the expression for the force acting on a current carrying conductor of length $L$ in a uniform magnetic field ’ $B$ ‘.

U [Delhi Comptt. I 2017]

Ans. Lorentz force

Expression in vector form $1 / 2$ Identification of pair of vectors Derivation of expression of force $1 / 2$ Lorentz magnetic force is force experienced by a charged particle of charge ’ $q$ ’ moving in magnetic field $\vec{B}$ with $\vec{v}$

$\vec{F_{m}} = q (\vec{v} \times \vec{B})$

$1 / 2$

[CBSE Marking Scheme, 2017]

Moving Charges And Magnetism

moving-charges-and-magnetism Question 29

Ans. Lorentz force

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Moving Charges And Magnetism

moving-charges-and-magnetism Question 29

Ans. Lorentz force

Table of Contents

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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