1
WB JEE 2018
+1
-0.25
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
$${{T \over 2}}$$
2
WB JEE 2018
+1
-0.25
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
B
C
D
3
WB JEE 2018
+1
-0.25
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
4
WB JEE 2018
+2
-0.5
A light charged particle is revolving in a circle of radius r in electrostatic attraction of a static heavy particle with opposite charge. How does the magnetic field B at the centre of the circle due to the moving charge depend on r?
A
$$B \propto {1 \over r}$$
B
$$B \propto {1 \over {{r^2}}}$$
C
$$B \propto {1 \over {{r^{3/2}}}}$$
D
$$B \propto {1 \over {{r^{5/2}}}}$$
EXAM MAP
Medical
NEET