1
WB JEE 2017
MCQ (More than One Correct Answer)
+2
-0
Change Language
Two long parallel wires separated by 0.1 m carry currents of 1A and 2A, respectively in opposite directions. A third current-carrying wire parallel to both of them is placed in the same plane such that it feels no net magnetic force. It is placed at a distance of
A
0.5 m from the 1st wire, towards the 2nd wire
B
0.2 m from the 1st wire, towards the 2nd wire.
C
0.1 m from the 1st wire, away from the 2nd wire
D
0.2 m from the 1st wire, away from the 2nd wire.
2
WB JEE 2017
MCQ (More than One Correct Answer)
+2
-0
Change Language
If $$\chi $$ stands for the magnetic susceptibility of a substance, $$\mu$$ for its magnetic permeability and $$\mu$$0 for the permeability of free space, then
A
for a paramagnetic substance : $$\chi $$ < 0, $$\mu$$ > 0
B
for a paramagnetic substance : $$\chi $$ > 0, $$\mu$$ > $$\mu$$0
C
for a diamagnetic substance : $$\chi $$ > 0, $$\mu$$ < 0
D
for a ferromagnetic substance : $$\chi $$ > 1, $$\mu$$ > $$\mu$$0
3
WB JEE 2017
MCQ (More than One Correct Answer)
+2
-0
Change Language
Let vn and En be the respective speed and energy of an electron in the nth orbit of radius rn, in a hydrogen atom, as predicted by Bohr's model. Then
A
plot of $${{{E_n}{r_n}} \over {{E_1}{r_1}}}$$ as a function of n is a straight line of slope 0
B
plot of $${{{r_n}{v_n}} \over {{r_1}{v_1}}}$$ as a function of n is a straight line of slope 1
C
plot of ln$$\left( {{{{r_n}} \over {{r_1}}}} \right)$$ as a function of ln (n) is a straight line of slope 2
D
plot of ln $$\left( {{{{r_n}{E_1}} \over {{E_n}{r_1}}}} \right)$$ as a function of ln (n) is a straight line of slope 4
4
WB JEE 2017
MCQ (More than One Correct Answer)
+2
-0
Change Language
A small steel ball bounces on a steel plate held horizontally. On each bounce the speed of the ball arriving at the plate is reduced by a factor e (coefficient of restitution) in the rebound, so that Vupward = eVdownward. If the ball is initially dropped from a height of 0.4 m above the plate and if 10 seconds later the bouncing ceases, the value of e is
A
$$\sqrt {{2 \over 7}} $$
B
$${{3 \over 4}}$$
C
$${{{13} \over {18}}}$$
D
$${{{17} \over {18}}}$$
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