HARD

Earn 100

In Thomson's experiment, if the velocity of electron is greater than the ratio of electric field $(E)$ and magnetic field $(i e, v > E / B)$ , then

50% studentsanswered this correctly

Important Questions on Moving Charges and Magnetism

HARD

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

In the

xy - plane

, the region

y > 0

has a uniform magnetic field

B_{1} \hat{k}

and the region

y < 0

has another uniform magnetic field

B_{2} \hat{k}

. A positively charged particle is projected from the origin along the positive

y - axis

with speed

v_{0} = π m s^{- 1}

t = 0

, as shown in the figure. Neglect gravity in this problem. Let

t = T

be the time when the particle crosses the

x - axis

from below for the first time. If

B_{2} = 4 B_{1}

, the average speed of the particle, in

m s^{- 1}

, along the

x - axis

in the time interval

T

is ________.

Question Image

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A proton with a kinetic energy of

2.0 eV

moves into a region of uniform magnetic field of magnitude

\frac{π}{2} \times 10^{- 3} T

. The angle between the direction of magnetic field and velocity of proton is

60^{o}

. The pitch of the helical path taken by the proton is ____

cm

. (Take, mass of proton

= 1.6 \times 10^{- 27} kg

and charge on proton

= 1.6 \times 10^{- 19} C

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A proton and an

α

- particle (with their masses in the ratio of

1 : 4

and charges in the ratio of

1 : 2

) are accelerated from rest through a potential difference

V .

If a uniform magnetic field

(B)

is set up perpendicular to their velocities, the ratio of the radii

r_{p} : r_{α}

of the circular paths described by them will be:

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

An electron is moving in a circular path under the influence of a transverse magnetic field of

3.57 \times 10^{- 2} T

. If, the value of

\frac{e}{m}

1 .76 \times 10^{11} C {kg}^{- 1}

, the frequency of revolution of the electron is

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A beam of protons with velocity

600 km s^{- 1}

enters a uniform magnetic field of

0.2 T

. The velocity makes an angle of

30 °

with the magnetic field. The radius of the helical path will be

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A rectangular region of dimensions $w \times I (w < < I)$ has a constant magnetic field into the plane of the paper as shown. On one side the region is bounded by a screen. On the other side positive ions of mass $m$ and charge $q$ are accelerated from rest and towards the screen by a parallel plate capacitor at constant potential difference $V < 0$ , and come out through a small hole in the upper plate. Which one of the following statements is correct regarding the charge on the ions that hit the screen?

Question Image

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A charge particle moving in magnetic field

B,

has the components of velocity along

B

as well as perpendicular to

B

. The path of the charge particle will be

HARD

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A charged particle is introduced at the origin

x = 0, y = 0, z = 0

with a given initial velocity

\vec{v}

. A uniform electric field

\vec{E}

and a uniform magnetic field

\vec{B}

exist everywhere. The velocity

\vec{v}

, electric field

\vec{E}

and a uniform magnetic field

\vec{B}

are given in the columns below

Column 1	Column 2	Column 3
1. Electron with $\vec{v} = 2 \frac{E_{0}}{B_{0}} \hat{x}$	(i) $\vec{E} = E_{0} \hat{z}$	(P) $\vec{B} = - B_{0} \hat{x}$
2. Electron with $\vec{v} = \frac{E_{0}}{B_{0}} \hat{y}$	(ii) $\vec{E} = - E_{0} \hat{y}$	(Q) $\vec{B} = B_{0} \hat{x}$
3.Proton with $\vec{v} = 0$	(iii) $\vec{E} = {- E}_{0} \hat{x}$	(R) $\vec{B} = B_{0} \hat{y}$
4. Proton with $\vec{v} = 2 \frac{E_{0}}{B_{0}} \hat{x}$	(iv) $\vec{E} = E_{0} \hat{x}$	(S) $\vec{B} = B_{0} \hat{z}$

In which case will the particle move in a straight line with a constant velocity?

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A particle of mass

m

and charge

q

with an initial velocity

v

is subjected to a uniform magnetic field

B

along the vertical direction. The particle will

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

When a charged particle enters a magnetic field at an angle of

60 °

with the field direction, it traces

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

An electron is moving with a velocity

2 \times 10^{6} m / s

along positive

x

-direction in the uniform electric field of

8 \times 10^{7} V / m

applied along positive

y

-direction. The magnitude and direction of a uniform magnetic field (in tesla) that will cause the electrons to move undeviated along its original path is

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A beam of protons with speed

4 \times 10^{5} m s^{- 1}

enters a uniform magnetic field of

0.3 T

at an angle

60 °

to the magnetic field, the pitch of the resulting helical path of protons is close to : (Mass of the proton

= 1.67 \times 10^{- 27} kg

, charge of the proton

= 1.69 \times 10^{- 19} C

)

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A negative test charge is moving near a long straight wire carrying a current. The force acting on the test charge is parallel to the direction of the current. The motion of the charge is:

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A proton and an alpha particle both enter a region of uniform magnetic field B, moving at right angles to the field B. if the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is 1 MeV, the energy acquired by the alpha particle will be:

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

An electron, a proton and an alpha particle having the same kinetic energy are moving in circular orbits of radii

r_{e}, r_{p}, r_{α}

respectively in a uniform magnetic field B. The relation between

r_{e}, r_{p}, r_{α}

is:

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

Ionized hydrogen atoms and

α

-particles with same momenta enters perpendicular to a constant magnetic field

B

. The ratio of their radii of their paths

r_{H} : r_{α}

will be

HARD

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A charged particle is introduced at the origin

x = 0, y = 0, z = 0

with a given initial velocity

\vec{v}

. A uniform electric field

\vec{E}

and a uniform magnetic field

\vec{B}

exist everywhere. The velocity

\vec{v}

, electric field

\vec{E}

and a uniform magnetic field

\vec{B}

are given in the columns below

Column 1	Column 2	Column 3
1. Electron with $\vec{v} = 2 \frac{E_{0}}{B_{0}} \hat{x}$	(i) $\vec{E} = E_{0} \hat{z}$	(P) $\vec{B} = - B_{0} \hat{x}$
2. Electron with $\vec{v} = \frac{E_{0}}{B_{0}} \hat{y}$	(ii) $\vec{E} = - E_{0} \hat{y}$	(Q) $\vec{B} = B_{0} \hat{x}$
3.Proton with $\vec{v} = 0$	(iii) $\vec{E} = {- E}_{0} \hat{x}$	(R) $\vec{B} = B_{0} \hat{y}$
4. Proton with $\vec{v} = 2 \frac{E_{0}}{B_{0}} \hat{x}$	(iv) $\vec{E} = E_{0} \hat{x}$	(S) $\vec{B} = B_{0} \hat{z}$

In which case would the particle move in a straight line along the negative direction of y axis

HARD

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

An electron is moving in a uniform magnetic field

\vec{B}

. The velocity

\vec{v}

of the electron is directed at an angle

θ

to the direction of the field where

\tan θ = \frac{3}{4}

. If the speed of the electron is

4 \times 10^{6} m s^{- 1}

and the strength of the magnetic field is

0.18 T

, then the distance moved by the electron along the field direction in the time it takes for the electron to complete one full orbit is approximately

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

A particle of mass

m

and charge

q

is incident on

X Z

plane with velocity

v

in a direction making angle

θ

with a uniform magnetic field applied along

X

-axis. The nature of motion performed by the particle is

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Motion in a Magnetic Field

The figure shows a region of length ' $l$ ' with a uniform magnetic field of $0.3 T$ in it and a proton entering the region with velocity $4 \times 10^{5} m s^{- 1}$ making an angle $60 °$ with the field. If the proton completes $10$ revolution by the time it cross the region shown, ' $l$ ' is close to (mass of proton $= 1.67 \times 10^{- 27} kg$ , charge of the proton $= 1.6 \times 10^{- 19} C$ )

Question Image

In Thomson's experiment, if the velocity of electron is greater than the ratio of electric field (E) and magnetic field (ie, v>E/B), then

Important Questions on Moving Charges and Magnetism

Learn and Prepare for any exam you want !

In Thomson's experiment, if the velocity of electron is greater than the ratio of electric field $(E)$ and magnetic field $(i e, v > E / B)$ , then