# MAGNETIC EFFECTS OF CURRENT Online Test

In case Hall effect for a strip having charge Q and area of cross-section A, the Lorentz force is ____.
Directly proportional to Q
Inversely proportional to Q
Inversely proportional to A
Directly proportional to A
A electron (q = 1.6 ( 10–19 C) is moving at right angle to the uniform magnetic field 3.534 ( 10–5 T. The time taken by the electron to complete a circular orbit is ____.
2 (s
4 (s
3 (s
1 (s
A very high magnetic field is applied to a stationary charge. Then the charge experiences ____.
A force in the direction of magnetic field
A force perpendicular to the magnetic field
A force in an arbitrary direction
No force
An electron is projected along the axis of a circular conductor carrying some current. Electron will experience force ____.
Along the axis
Perpendicular to the axis
At an angle of 4o with axis
No force experienced
An electron moving with a uniform velocity along the positive x-direction enters a magnetic field directed along the positive y-direction. The force on the electron is directed along ____.
Positive y-direction
Negative y-direction
Positive z-direction
Negative z-direction
The cyclotron frequency of an electron grating in a magnetic field of 1 T is approximately ____.
28 MHz
280 MHz
2.8 GHz
28 GHz
An electron and a proton have equal kinetic energies. They enter in a magnetic field perpendicularly, Then ____.
Both will follow a circular path with same radius
Both will follow a helical path
Both will follow a parabolic path
All the statements are false
Two ions having masses in the ratio 1 : 1 and charges 1 : 2 are projected into uniform magnetic field perpendicular to the field with speeds in the ratio 2 : 3. The ratio of the radii of circular paths along which the two particles move is ____.
4 : 3
2 : 3
3 : 1
1 : 4
A charged particle is released from rest in a region of steady uniform electric and magnetic fields which are parallel to each other the particle will move in a ____.
Straight line
Circle
Helix
Cycloid
An electron (mass = 9( 10–31kg. Charge = 1.6 ( 10–19C) whose kinetic energy is 7.2 ( 10–18 joule is moving in a circular orbit in a magnetic field of 9 ( 10–5 weber/m2. The radius of the orbit is ____.
1.25 cm
2.5 cm
12.5 cm
25.0 cm
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MAGNETIC EFFECTS OF CURRENT

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