1
WB JEE 2017
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A particle with charge e and mass m, moving along the X-axis with a uniform speed u, enters a region where a uniform electric field E is acting along the Y-axis. The particle starts to move in a parabola. Its focal length (neglecting any effect of gravity) is
A
$${{{2m{u^2}} \over {eE}}}$$
B
$${{{eE} \over {2m{u^2}}}}$$
C
$${{{mu} \over {2eE}}}$$
D
$${{{m{u^2}} \over {2eE}}}$$
2
WB JEE 2017
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A unit negative charge with mass M resides at the mid-point of the straight line of length 2a adjoining two fixed charges of magnitude +Q each. If it is given a very small displacement x(x << a) in a direction perpendicular to the straight line, it will
A
come back to its original position and stay there
B
execute oscillations with frequency $${1 \over {2\pi }}\sqrt {{Q \over {2\pi {\varepsilon _0}M{a^3}}}} $$
C
fly to infinity
D
execute oscillations with frequency $${1 \over {2\pi }}\sqrt {{Q \over {2\pi {\varepsilon _0}M{a^2}}}} $$
3
WB JEE 2017
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Consider the circuit given here. The potential difference VBC between the points B and C is

WB JEE 2017 Physics - Current Electricity Question 20 English
A
1 V
B
0.5 V
C
0 V
D
$$-$$ 1 V
4
WB JEE 2017
MCQ (More than One Correct Answer)
+2
-0
Change Language
If the pressure, temperature and density of an ideal gas are denoted by p, T and $$\rho $$, respectively, the velocity of sound in the gas is
A
proportional to $$\sqrt \rho $$, when T is constant
B
proportional to $$\sqrt T $$
C
proportional to $$\sqrt p $$, when $$\rho $$ is constant
D
proportional to T.
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