CLASS 12 PHYSICS -AJAY KR GUPTA

Two objects of charges q₁ and q₂ repel each other when:

• q₁q₂<0

• q₁q₂>0

• q₁q₂=0

• Cannot be ascertained as sign of charges is not given.

Which of the following charges is not possible for an object to acquire?

• - 3.2 × 10^-19C

• +2.4 x 10^-19C

• +3.2 x 10^-19 C

• - 4.8 x 10^-19C

Two point charges placed in a medium of dielectric constant 5 are at a distance r between them, experience an electrostatic force 'F'. The electrostatic force between them in vacuum at the same distance r will be:

• 5F

• F/2

• F

• F/5

SI unit of electrical permittivity is

• N-m²C^-2

• Am ^-2

• NC^-1

• C²N^-1m^-2

A force of 2.25 N acts on a chrage of 15 x 10-4 C. The intensity of electric field at that point is

• 150 NC^-1

• 1500NC^-1

• 15NC^-1

• 1.5NC^-1

Two equal and opposite charges each of 2C are placed at a distance of 0.04 m. Dipole moment of the system will be

• 6×10^-8 C-m

• 8 x 10² C-m

• 1.5 x 10² C-m

• 8x10^-2C-m

In an electric field E, the torque acting on a dipole moment of p , is

• p. E

• p x E

• zero

• E x p

When an electric dipole p is placed in a uniform electric field E, then at what angle between p and E the value of torque will be maximum?

• 90°

• 45°

• 180°

• 0°

The SI unit of electric flux is

• Volt /Newton

• Newton /coulomb

• Newton x metre² / coulomb

• volt x metre²

The intensity of electric field at the surface of conducting hollow sphere is 10 NC^-1 and its radius is 10 cm. The value of electric field at the centre of sphere is

• zero

• 10 NC^-1

• 100 NC^-1

• 1 NC^-1