1. . The corpuscular theory of light was put forward by:
(A) Einstein
(B) Max Planck
(C) Young
(D) Newton
2. . Niels Bohr put forward his theory in:
(A) 1887
(B) 1902
(C) 1913
(D) 1917
3. . When an electron goes from a higher energy level to a lower energy level, it:
(A) Emits light
(B) Does not emit light
(C) Absorbs light
(D) None of these
4. . Laser is a device which can produce:
(A) An intense beam of light
(B) Coherent light
(C) Monochromatic light
(D) All of these
5. . The most widely used types of gas lasers are:
(A) Helium
(B) Neon
(C) Carbon dioxide
(D) All of these
6. . The metastable states of atoms are:
(A) Excited atomic states of long duration
(B) De-excited atomic state
(C) Ground states of atom
(D) None of these
7. . The excited atoms return to their ground state in:
(A) 10⁻⁸ sec
(B) 10⁻⁵ sec
(C) 10⁻³ sec
(D) 10¹⁵ sec
8. . An atom can exist in metastable state for:
(A) 10⁻⁵ sec
(B) 10⁻³ sec
(C) 10⁻⁸ sec
(D) 10⁻¹⁰ sec