1.In general, metallic ropes are suspended on the
carriers which take inflammable material. The
reason is
a) There speed is controlled
b) To keep the centre of gravity of the carrier
nearer to the earth
c) To keep the body of the carrier in contact with
the earth
d) Nothing should be placed under the carrier
Explanation: For providing path to charge induced on the surface of the carriers which take inflammable material.
2.Three equal charges are placed on the three
corners of a square. If the force between \[q_{1}\] and
\[q_{2}\] is \[F_{12}\] and that between \[q_{1}\] and \[q_{3}\] is \[F_{13}\] , the
ratio of magnitudes \[\frac{F_{12}}{F_{13}}\]
is
a) 1/2
b) 2
c) \[1/\sqrt{2}\]
d) \[\sqrt{2}\]
Explanation:
3. ABC is a right angled triangle in which AB = 3 cm
and BC=4 cm . And \[\angle ABC=\pi /2\] . The three
charges +15,+12 and -20 e.s.u. are placed
respectively on A , B and C . The force acting on
B is
a) 125 dynes
b) 35 dynes
c) 25 dynes
d) zero
Explanation:
4. With the rise in temperature, the dielectric
constant K of a liquid
a) Increases
b) Decreases
c) Remains unchanged
d) Charges erratically
Explanation: With temperature rise, dielectric constant of liquid decreases.
5. Two charges \[q_{1}\] and \[q_{2}\] are placed in vacuum at a
distance d and the force acting between them is
F . If a medium of dielectric constant 4 is
introduced around them, the force now will be
a) 4 F
b) 2 F
c) \[\frac{F}{2}\]
d) \[\frac{F}{4}\]
Explanation: In the presence of medium force becomes
6. Force of attraction between two point charges Q
and – Q separated by d metre is \[F_{e}\] . When these
charges are placed on two identical spheres of
radius \[R=0.3 d\] whose centres are d metre apart,
the force of attraction between them is
a) Greater than \[ F_{e}\]
b) Equal to \[ F_{e}\]
c) Less than\[ F_{e}\]
d) Less than \[ F_{e}\]
Explanation: Separation between the spheres is not too large as compared to their radius so due to induction effect redistribution of charge takes place. Hence effective charge separation decreases so force increases.
7. When \[10^{14}\] electrons are removed from a neutral
metal sphere, the charge on the sphere becomes
a) \[16\mu C\]
b) \[-16\mu C\]
c) \[32\mu C\]
d) \[-32\mu C\]
Explanation:
8. A force F acts between sodium and chlorine ions
of salt (sodium chloride) when put 1cm apart in
air. The permittivity of air and dielectric constant
of water are \[\epsilon_{0}\] and K respectively. When a piece
of salt is put in water electrical force acting
between sodium and chlorine ions 1 cm apart is
a) \[\frac{F}{K}\]
b) \[\frac{FK}{\epsilon_{0}}\]
c) \[\frac{F}{ K \epsilon_{0}}\]
d) \[\frac{F \epsilon_{0}}{ K}\]
Explanation:
9.A conductor has \[14.4 \times 10^{-19} coulombs\] positive
charge. The conductor has (Charge on electron =1.6 \[\times 10^{-19} coulombs)\]
a) 9 electrons in excess
b) 27 electrons in short
c) 27 electrons in excess
d) 9 electrons in short
Explanation:
10. The value of electric permittivity of free space is
a) \[9 \times 10^{9} NC^{2}/m^{2}\]
b) \[8.85 \times 10^{-12}Nm^{2}/C^{2}sec\]
c) \[8.85 \times 10^{-12}C^{2}/Nm^{2}\]
d) \[9 \times 10^{9}C^{2}/Nm^{2}\]
Explanation: \[8.85 \times 10^{-12}C^{2}/Nm^{2}\]