1
WB JEE 2019
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A particle with charge q moves with a velocity v in a direction perpendicular to the directions of uniform electric and magnetic fields, E and B respectively, which are mutually perpendicular to each other. Which one of the following gives the condition for which the particle moves undeflected in its original trajectory?

WB JEE 2019 Physics - Magnetism Question 25 English
A
$$v = {E \over B}$$
B
$$v = {B \over E}$$
C
$$v = \sqrt {{E \over B}} $$
D
$$v = q{B \over E}$$
2
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
A proton of mass m moving with a speed v (< < c, velocity of light in vacuum) completes a circular orbit in time T in a uniform magnetic field. If the speed of the proton is increased to $$\sqrt 2 $$ v, what will be time needed to complete the circular orbit?
A
$$\sqrt 2 $$T
B
T
C
$${{T \over {\sqrt 2 }}}$$
D
$${{T \over 2}}$$
3
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
A uniform current is flowing along the length of an infinite, straight, thin, hollow cylinder of radius R. The magnetic field B produced at a perpendicular distance d from the axis of the cylinder is plotted in a graph. Which of the following figures looks like the plot?
A
WB JEE 2018 Physics - Magnetism Question 18 English Option 1
B
WB JEE 2018 Physics - Magnetism Question 18 English Option 2
C
WB JEE 2018 Physics - Magnetism Question 18 English Option 3
D
WB JEE 2018 Physics - Magnetism Question 18 English Option 4
4
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
A circular loop of radius r of conducting wire connected with a voltage source of zero internal resistance produces a magnetic field B at its centre. If instead, a circular loop of radius 2r, made of same material, having the same cross-section is connected to the same voltage source, what will be the magnetic field at its centre?
A
$${B \over 2}$$
B
$${B \over 4}$$
C
2B
D
B
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