1
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
A system of three charges are placed as shown in the figure :

If D >> d, the potential energy of the system is best given by :
A
$${1 \over {4\pi {\varepsilon _0}}}\left[ { {{{q^2}} \over d} + {{qQd} \over {{D^2}}}} \right]$$
B
$${1 \over {4\pi {\varepsilon _0}}}\left[ { - {{{q^2}} \over d} - {{qQd} \over {2{D^2}}}} \right]$$
C
$${1 \over {4\pi {\varepsilon _0}}}\left[ { - {{{q^2}} \over d} - {{qQd} \over {{D^2}}}} \right]$$
D
$${1 \over {4\pi {\varepsilon _0}}}\left[ { - {{{q^2}} \over d} + {2{qQd} \over {{D^2}}}} \right]$$
2
JEE Main 2019 (Online) 8th April Evening Slot
+4
-1
A positive point charge is released from rest at a distance r0 from a positive line charge with uniform density. The speed (v) of the point charge, as a function of instantaneous distance r from line charge, is proportional to :-
A
$$v \propto \left( {{r \over {{r_0}}}} \right)$$
B
$$v \propto \ln \left( {{r \over {{r_0}}}} \right)$$
C
$$v \propto {e^{ + r/{r_0}}}$$
D
$$v \propto \sqrt {\ln \left( {{r \over {{r_0}}}} \right)}$$
3
JEE Main 2019 (Online) 8th April Evening Slot
+4
-1
The electric field in a region is given by $$\mathop E\limits^ \to = \left( {Ax + B} \right)\mathop i\limits^ \wedge$$ , where E is in NC–1 and x is in metres. The values of constants are A = 20 SI unit and B = 10 SI unit. If the potential at x = 1 is V1 and that at x = –5 is V2, then V1 – V2 is :-
A
–520 V
B
180 V
C
–48 V
D
320 V
4
JEE Main 2019 (Online) 8th April Morning Slot
+4
-1
The bob of a simple pendulum has mass 2g and a charge of 5.0 μC. It is at rest in a uniform horizontal electric field of intensity 2000 V/m. At equilibrium, the angle that the pendulum makes with the vertical is : (take g = 10 m/s2)
A
tan–1(5.0)
B
tan–1(2.0)
C
tan–1(0.5)
D
tan–1(0.2)
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