1. The law, governing the force between electric
charges is known as
a) Ampere's law
b) Ohm's law
c) Faraday's law
d) Coulomb's law
Explanation: Coulomb's law is used to calculate the force between charges.
2. When the distance between the charged particles
is halved, the force between them becomes
a) One-fourth
b) Half
c) Double
d) Four times
Explanation:
3.There are two charges +1 microcoulombs and +5
microcoulombs. The ratio of the forces acting on
them will be
a) 1 : 5
b) 1 : 1
c) 5 : 1
d) 1 : 25
Explanation: The same force will act on both bodies although their directions will be different.
4. A charge \[q_{1}\] exerts some force on a second charge
\[q_{2}\] . If third charge \[q_{3}\] is brought near, the force
of \[q_{1}\] exerted on \[q_{2}\]
a) Decreases
b) Increases
c) Remains unchanged
d) Increases if \[q_{3}\] is of the same sign as \[q_{1}\] and
decreases if \[q_{3}\] is of opposite sign
Explanation: Remains unchanged
5. \[F_{g}\] and \[F_{e}\] represents gravitational and
electrostatic force respectively between electrons
situated at a distance 10 cm. The ratio of \[F_{g}/F_{e}\] is
of the order of
a) \[10^{42}\]
b) 10
c) 1
d) \[10^{-43}\]
Explanation:
6. The ratio of the forces between two small spheres
with constant charge (a) in air (b) in a medium of
dielectric constant K is
a) 1 : K
b) K : 1
c) \[1 : K^{2}\]
d) \[ K^{2} :1\]
Explanation:
7. A soap bubble is given a negative charge, then its
radius
a) Decreases
b) Increases
c) Remains unchanged
d) Nothing can be predicted as information is
insufficient
Explanation: Due to mutual repulsion of charges distributed on the surface of bubble.
8. Four charges are arranged at the corners of a
square ABCD , as shown in the adjoining figure.
The force on the charge kept at the centre O is
a) Zero
b) Along the diagonal
AC
c) Along the diagonal BD
d) Perpendicular to side AB
Explanation: We put a unit positive charge at O. Resultant force due to the charge placed at A and C is zero and resultant charge due to B and D is towards D along the diagonal BD.
9.In the absence of other conductors, the surface
charge density
a) Is proportional to the charge on the conductor
and its surface area
b) Inversely proportional to the charge and
directly proportional to the surface area
c) Directly proportional to the charge and
inversely proportional to the surface area
d) Inversely proportional to the charge and the
surface area
Explanation:
10. A body can be negatively charged by
a) Giving excess of electrons to it
b) Removing some electrons from it
c) Giving some protons to it
d) Removing some neutrons from it
Explanation: Excess of electron gives the negative charge on body