Two identical non-conducting solid spheres of same mass and charge are suspended in air from a common point by two non-conducting, massless strings of same length. At equilibrium, the angle between the strings is $$\alpha$$. The spheres are now immersed in a dielectric liquid of density 800 kg m$$-$$3 and dielectric constant 21. If the angle between the strings remains the same after the immersion, then
A
electric force between the spheres remains unchanged
B
electric force between the spheres reduces
C
mass density of the spheres is 840 kg m$$-$$3
D
the tension in the strings holding the spheres remains unchanged
2
JEE Advanced 2020 Paper 1 Offline
MCQ (More than One Correct Answer)
+4
-2
A uniform electric field, $$\overrightarrow E = - 400\sqrt 3 \widehat y$$ NC−1
is applied in a region. A charged particle of mass m
carrying positive charge q is projected in this region with an initial speed of 2$$\sqrt {10} $$ $$ \times $$ 106 ms−1
. This
particle is aimed to hit a target T, which is 5 m away from its entry point into the field as shown
schematically in the figure. Take $${q \over m}$$
= 1010 Ckg−1
. Then
A
the particle will hit T if projected at an angle 45o
from the horizontal
B
the particle will hit T if projected either at an angle 30o or 60o
from the horizontal
C
time taken by the particle to hit T could be $$\sqrt {{5 \over 6}} $$ $$\mu $$s as well as $$\sqrt {{5 \over 2}} $$ $$\mu $$s
D
time taken by the particle to hit T is $$\sqrt {{5 \over 3}} $$ $$\mu $$s
3
JEE Advanced 2020 Paper 1 Offline
MCQ (More than One Correct Answer)
+4
-2
Shown in the figure is a semicircular metallic strip that has thickness t and resistivity $$\rho $$. Its inner
radius is R1 and outer radius is R2. If a voltage V0 is applied between its two ends, a current I flows
in it. In addition, it is observed that a transverse voltage $$\Delta $$V develops between its inner and outer
surfaces due to purely kinetic effects of moving electrons (ignore any role of the magnetic field due
to the current). Then (figure is schematic and not drawn to scale)
the outer surface is at a higher voltage than the inner surface
C
the outer surface is at a lower voltage than the inner surface
D
$$\Delta $$V $$ \propto $$ I2
4
JEE Advanced 2019 Paper 1 Offline
MCQ (More than One Correct Answer)
+4
-1
In the circuit shown, initially there is no charge on the capacitors and keys S1 and S2 are open. The values of the capacitors are C1 = 10$$\mu $$F, C2 = 30$$\mu $$F and C3 = C4 = 80$$\mu $$F.
Which of the statement(s) is/are correct?
A
The key S1 is kept closed for long time such that capacitors are fully charged. Now, key S2 is closed, at this time, the instantaneous current across 30$$\Omega $$ resistor (between points P and Q) will be 0.2 A (round off to 1st decimal place).
B
If key S1 is kept closed for long time such that capacitors are fully charged, the voltage across the capacitor C1 will be 4V.
C
At time t = 0, the key S1 is closed, the instantaneous current in the closed circuit will be 25 mA.
D
If key S1 is kept closed for long time such that the capacitors are fully charged, the voltage difference between points P and Q will be 10 V.
