1
JEE Main 2019 (Online) 10th April Evening Slot
+4
-1
A coil of self inductance 10 mH and resistance 0.1 $$\Omega$$ is connected through a switch to a battery of internal resistance 0.9 $$\Omega$$. After the switch is closed, the time taken for the current to attain 80% of the saturation value is: [take ln 5 = 1.6]
A
0.324 s
B
0.002 s
C
0.103 s
D
0.016 s
2
JEE Main 2019 (Online) 10th April Morning Slot
+4
-1
The electric field of a plane electromagnetic wave is given by
$$\overrightarrow E = {E_0}\widehat i\cos (kz)cos(\omega t)$$
The corresponding magnetic field $$\overrightarrow B$$ is then given by
A
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\sin (kz)\sin (\omega t)$$
B
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\sin (kz)\cos (\omega t)$$
C
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\cos (kz)\sin (\omega t)$$
D
$$\overrightarrow B = {{{E_0}} \over C}\widehat k\sin (kz)\cos (\omega t)$$
3
JEE Main 2019 (Online) 10th April Morning Slot
+4
-1
A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10A, then the input voltage and current in the primary coil are :
A
220 V and 20 A
B
220 V and 10A
C
440 V and 5A
D
440 V and 20 A
4
JEE Main 2019 (Online) 9th April Evening Slot
+4
-1
A very long solenoid of radius R is carrying current I(t) = kte–at(k > 0), as a function of time (t $$\ge$$ 0). counter clockwise current is taken to be positive. A circular conducting coil of radius 2R is placed in the equatorial plane of the solenoid and concentric with the solenoid. The current induced in the outer coil is correctly depicted, as a function of time, by :-
A
B
C
D
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