1. . The corpuscular theory of light was put forward by
(A) Einstein
(B) Newton
(C) Young
(D) Max Planck
2. . Neil Bohr put forward his theory in
(A) 1887
(B) 1902
(C) 1917
(D) 1913
3. . When an electron goes from higher energy level to 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) All of these
(B) Coherent light
(C) Monochromatic light
(D) An intense beam of light
5. . The most widely used types of gas lasers are
(A) All of these
(B) Neon
(C) Carbon dioxide
(D) Helium
6. . The meta-stable states of atoms are
(A) Ground states of atom
(B) De-excited atomic state
(C) Excited atomic states of long period
(D) None of these
7. . The excited atoms return to their ground state in
(A) 10⁻³ sec
(B) 10⁻⁵ sec
(C) 10⁻⁸ sec
(D) 10¹⁵ sec
8. . An atom can exist in meta-stable state for
(A) 10⁻³ sec
(B) 10⁻⁵ sec
(C) 10⁻⁸ sec
(D) 10⁻¹⁰ sec