1
JEE Main 2019 (Online) 12th January Evening Slot
+4
-1
A 10 m long horizontal wire extends from North East to South West. It is falling with a speed of 5.0 ms–1, at right angles to the horizontal component of the earth's magnetic field of 0.3 $$\times$$ 10–4 Wb/m2. The value of the induced emf in wire is :
A
0.3 $$\times$$ 10–3 V
B
2.5 $$\times$$ 10–3 V
C
1.5 $$\times$$ 10–3 V
D
1.1 $$\times$$ 10–3 V
2
JEE Main 2019 (Online) 11th January Evening Slot
+4
-1
A copper wire is wound on a wooden frame, whose shape is that of an equilateral triangle. If the linear dimension of each side of the frame is increased by a factor of 3, keeping the number of turns of the coil per unit length of the frame the same, then the self inductance of the coil:
A
decreases by a factor of $$9\sqrt 3$$
B
increases by a factor of 27
C
decreases by a factor of 9
D
increases by a factor of 3
3
JEE Main 2019 (Online) 11th January Morning Slot
+4
-1
There are two long co-axial solenoids of same length $$l$$. The inner and outer coils have radii r1 and r2 and number of turns per unit length n1 and n2, respectively. The ratio of mutual inductance to the self - inductance of the inner-coil is :
A
$${{{n_2}} \over {{n_1}}}.{{{r_2}^2} \over {{r_1}^2}}$$
B
$${{{n_2}} \over {{n_1}}}$$
C
$${{{n_1}} \over {{n_2}}}$$
D
$${{{n_2}} \over {{n_1}}}.{{{r_1}} \over {{r_2}}}$$
4
JEE Main 2019 (Online) 10th January Evening Slot
+4
-1
The self induced emf of a coil is 25 volts. When the current in it is changed at uniform rate from 10 A to 25 A in 1s, the change in the energy of the inductance is -
A
740 J
B
637.5 J
C
540 J
D
437.5 J
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