1
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
An alternating current is flowing through a series L-C-R circuit. It is found that the current reaches a value of 1 mA at both 200 Hz and 800 Hz frequency. What is the resonance frequency of the circuit?
A
600 Hz
B
300 Hz
C
500 Hz
D
400 Hz
2
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.
3
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
$$B \propto {1 \over {{r^{5/2}}}}$$
4
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
$$E \propto {1 \over {{t^3}}}$$
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