Moving Charges and Magnetic Effects Test

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Moving Charges and Magnetic Effects Test - 5

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Weekly Quiz Competition

Question 1
1 / -0

cyclotron is used to

A
accelerate charged particles or ions to low voltages

B
decelerate charged particles or ions to high voltages

C
accelerate charged particles or ions to high voltages

D
accelerate charged particles or ions to high energies

Solution

Cyclotron is a particle accelerator, which uses electric field to accelerate the charged particle and magnetic field to make it move in a circular path. During acceleration in the electric field, the particle acquires high energies of the order of a few million electron volts.
Question 2
1 / -0

A proton is moving in a uniform magnetic field B in a circular path of radius 'a' in a direction perpendicular to z-axis along which the field B exists. Calculate the angular momentum if charge on the proton is 'e'.

A

B
eB²a

C
a²eB

D
aeB
Question 3
1 / -0

An electron of mass m and charge q is travelling with a speed v along a circular path of radius r at a right angle to a uniform magnetic field of intensity B. If the speed of the electron is doubled and the intensity of magnetic field is halved, the resulting path would have a radius

A
2r

B
4r

C

D
Question 4
1 / -0

An electron beam is moving between two parallel plates having an electric field 1.125 x 10^-6 N/m. A magnetic field 3 x 10^-10 T is also applied so that the beam does not deflect. The velocity of the electron is

A
4225 m/s

B
3750 m/s

C
2750 m/s

D
3200 m/s
Question 5
1 / -0

A 600 mm long solenoid has 50 turns on it and is wound on an iron rod of 7.5 mm radius. Find the flux through the solenoid when the current in it is 3 A.
(Given: The relative permeability of iron is 600.)

A
1.66 kWb

B
1.66 Wb

C
1.66 mWb

D
1.66 μWb
Question 6
1 / -0

If a current I is flowing in a staight wire parallel to x axis and magnetic field is there in the y axis then

A
The wire experiences force in x direction

B
The wire experiences no force

C
The wire experiences force in z direction

D
The wire experiences force in y direction

Solution

force experienced by a conductor of length l carrying current I placed in magnetic field B is given by
Question 7
1 / -0

When an electron moves in a magnetic field in a direction perpendicular to the field, then its path will be

A
circular

B
elliptical

C
parabolic

D
helical
Question 8
1 / -0

Correct unit of magnetic field is

A
Ampere turns

B
Amperes

C
Newton coulombs

D
Tesla

Solution

The SI unit of magnetic field is Tesla (T).
Question 9
1 / -0

A beam of electrons passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off and the same magnetic field is maintained, the electrons move

A
in an elliptical orbit

B
in a circular orbit

C
along a parabolic path

D
along a straight line
Question 10
1 / -0

Current i is carried in a wire of length L. If the wire is turned into a circular coil, the maximum magnitude of torque in a given magnetic field B will be

A

B

C

D
Question 11
1 / -0

A vertical circular coil of radius 0.1 m and having 10 turns carries a steady current. When the plane of the coil is normal to the magnetic meridian, a neutral point is observed at the centre of the coil. If B_H = 0.314 ×10^-4 T, then what is the current in the coil?

A
0.5 A

B
0.25 A

C
2 A

D
1 A
Question 12
1 / -0

A charged particle is undergoing a circular motion in a magnetic field. The time period is independent of the

A
speed

B
mass

C
charge

D
intensity of magnetic field
Question 13
1 / -0

A proton and an alpha particle enter in a uniform magnetic field with the same velocity. The period of revolution of the alpha particle will be

A
four times that of the proton

B
two times that of the proton

C
three times that of the proton

D
five times that of the proton
Question 14
1 / -0

A wire PQR is bent as shown in the figure and is placed in a region of a uniform magnetic field B. The length of PQ = length of QR = L. A current l ampere flows through the wire as shown. The magnitude of the force on PQ and QR respectively will be

A
BIL and 0

B
2 BIL and 0

C
0 and BIL

D
0 and 0
Question 15
1 / -0

Consider the motion of a charged particle in a uniform magnetic field directed into the paper.If velocity v of the particle is in the plane of the paper the charged particle will

A
describe a circle

B
describe a straight line

C
describe a hyperbola

D
describe an ellipse

Solution
Question 16
1 / -0

A charged particle with charge q enters a region of constant, uniform and mutually orthogonal fields and with a velocity ,perpendicular to both and , and comes out without any change in the magnitude or the direction of . Then,

A

B

C

D
Question 17
1 / -0

A direct current is sent through a helical wire coil or spring. The coil

A
tends to get shorter

B
tends to get longer

C
tends to rotate about its axis

D
None of these
Question 18
1 / -0

At a point on the right bisector of a magnetic dipole, the magnetic

A
potential is zero at all points on the right bisector

B
potential varies as

C
field varies as r²

D
field is perpendicular to the axis of dipole
Question 19
1 / -0

An α-particle with a specific charge of 2.5 x10⁷ C-kg^-1 moves with a speed of 2x10⁵ ms^-1 in a perpendicular magnetic field of 0.05 T. Then, the radius of the circular path described by it is

A
8 cm

B
4 cm

C
16 cm

D
2 cm
Question 20
1 / -0

correct expression for force on a current carrying conductor of length dl in a magnetic field is

A

B

C

D

Solution