Moving Charges and Magnetism

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Answer – (a)

Explanation- in biot savarts law magnetic field is perpendicular to v

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer – (d)

Explanation- it is determined by its pitch

Pitch = $\frac{2\pi mvcos\theta }{Bq}$ = constant

So charge by mass ratio is also constant

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Explanation- magnetic field produced by a long straight current carrying wire is

B= $\frac{{\mu }_{0}I}{2\pi r}$ = $\frac{{\mu }_{0}I}{2\pi h}$ , for h height distance

Magnetic force on small conductor is F= ilBsin $\theta$ = ilB

Also force, F =mg = $\frac{{\mu }_0{I}^2}{2\pi r}$ l

h

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation- applying expression in different situation

For i_G (G+R₁) = 2 , for 2V range

i_G (G+R₁+R₂) = 20 , for 20V range

i_G (G+R₁+R₂+R₃) = 2 , for 200V range

on solving we get R₁= 1990ohm, R₂= 18kohm, R₃= 180k ohm

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Explanation- In Biot-Savart’s law, magnetic field B is parallel (II) to id × r and idl have its direction along the direction of flow of current.

Here, for the direction of magnetic field, At dl2, located at (0, R,0) due to wir

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Explanation- considering magnetic field along B=Bk and electron enters with a velocity v=vi into a cubical region

The force on electron using Lorentz force = -e (vi $*$ Bk)= evBi

So the force F= -eE₀ k accelerates along z axis whi

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Explanation- for a charge particle to move in circular path

Mv²/r = qvB

v/r=w= bq/m

w= v/r = $\frac{L{T}^{-1}}{L}$ = T-1

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Explanation- general formula for magnetic field at center is

B= $\frac{{\mu }_{0}I}{4\pi r}\left(\theta \right)$

B1= $\frac{{\mu }_{0}I}{4\pi r}\left(\frac{\pi }{2}\right)=\frac{{\mu }_{0}I}{8r}$ k for xy plane

B2= $\frac{{\mu }_{0}I}{8r}$ i for zy plane

B3= $\frac{{\mu }_{0}I}{8r}$ j for xz plane

After joining together B= $\frac{{\mu }_{0}I}{8\pi r}$  (i+j+k)

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation – in biot savart law, magnetic field B is parallel to idlr and idl have its direction along the direction of flow of current.

Here, for the direction of magnetic field at O₂, due to wire carrying I₁ current is B| pa

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation – here, the condition of magnetic resonance is violated.

When the frequency of radio frequency field were doubled, the time period of the radio frequency field were halved. Therefore, the duration in which particle