Electric Charges and Fields — Physics STD 12 Science — Question

The theory of quantisation of electric charge was given by:

Particle like behavior of light arises from the fact that each quanta of light has definite ...X... and a fixed value of ...Y.. just like a particle, Here, X and Y refer to?

For the ground state, the electron in the H-atom has an angular momentum = h, according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible directions. In actuality, this is not true,

The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation:

Shown in the figure here is a convergent lens placed inside a cell filled with a liquid. The lens has focal length + 20 cm when in air and its material has refractive index 1.50. If the liquid has refractive index 1.60, the focal length of the system is

(a) + 80 cm

(b) – 80 cm

(c) – 24 cm

(d) –100 cm

Photoelectric effect is the phenomenon in which?

A radio isotope has a half life of 75 years. The fraction of the atoms of this material that would decay in 150 years will be

(a) 66.6%

(b) 85.5%

(c) 62.5%

(d) 75%

A galvanometer has a resistance of 25 ohm and a maximum of 0.01 A current can be passed through it.  In order to change it into an ammeter of range 10 A, the shunt resistance required is

(a) 5/999 ohm

(b) 10/999 ohm

(c) 20/999 ohm

(d) 25/999 ohm

A cube of side b  has a charge q at each of its vertices. The electric field due to this charge distribution at the centre of this cube will be

(a)

(b)

(c)

(d) Zero