1
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
An electric bulb, a capacitor, a battery and a switch are all in series in a circuit. How does the intensity of light vary when the switch is turn on?
A
continues to increase gradually
B
gradually increases for sometime and then becomes steady
C
sharply rises initially and then gradually decreases
D
gradually increases for sometime and then gradually decreaes.
2
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
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
$$B \propto {1 \over {{r^{5/2}}}}$$
3
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
As shown in the figure, a rectangular loop of conducting wire is moving away with a constant velocity v in a perpendicular direction from a very long straight conductor carrying a steady current I. When the breadth of the rectangular loop is very small compared to its distance from the straight conductor, how does the emf. E induced in the loop vary with time t?

WB JEE 2018 Physics - Electromagnetic Induction Question 9 English
A
$$E \propto {1 \over {{t^2}}}$$
B
$$E \propto {1 \over t}$$
C
$$E \propto \ln (t)$$
D
$$E \propto {1 \over {{t^3}}}$$
4
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A solid spherical ball and a hollow spherical ball of two different materials of densities $$\rho $$1 and $$\rho $$2 respectively have same outer radii and same mass. What will be the ratio, the moment of inertia (about an axis passing through the centre) of the hollow sphere to that of the solid sphere?
A
$${{{\rho _2}} \over {{\rho _1}}}$$$${{{\left( {1 - {{{\rho _2}} \over {{\rho _1}}}} \right)}^{{5 \over 3}}}}$$
B
$${{{\rho _2}} \over {{\rho _1}}}\left[ {1 - {{\left( {1 - {{{\rho _2}} \over {{\rho _1}}}} \right)}^{{5 \over 3}}}} \right]$$
C
$${{{\rho _2}} \over {{\rho _1}}}$$$${{{\left( {1 - {{{\rho _1}} \over {{\rho _2}}}} \right)}^{{5 \over 3}}}}$$
D
$${{{\rho _2}} \over {{\rho _1}}}\left[ {1 - {{\left( {1 - {{{\rho _1}} \over {{\rho _2}}}} \right)}^{{5 \over 3}}}} \right]$$
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