WB JEE 2018 | Magnetism Question 24 | Physics

WB JEE 2018

MCQ (Single Correct Answer)

-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?

$$\sqrt 2 $$T

$${{T \over {\sqrt 2 }}}$$

$${{T \over 2}}$$

WB JEE 2018

MCQ (Single Correct Answer)

-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?

WB JEE 2018 Physics - Magnetism Question 20 English Option 1

WB JEE 2018 Physics - Magnetism Question 20 English Option 2

WB JEE 2018

MCQ (Single Correct Answer)

-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?

$${B \over 2}$$

$${B \over 4}$$

WB JEE 2018

MCQ (Single Correct Answer)

-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?

$$B \propto {1 \over r}$$

$$B \propto {1 \over {{r^2}}}$$

$$B \propto {1 \over {{r^{3/2}}}}$$

$$B \propto {1 \over {{r^{5/2}}}}$$

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