Unit 2- Electrons

Question 1

Electronvolt

Answer 1

An eV is the energy acquired by an electron accelerated through a p.d. of 1V

Question 2

De Broglie wavelength

Answer 2

Particle are observed to behave like waves with wavelength= Plank constant / momentum of particle

Question 3

Photoelectric effect

Answer 3

Emission of electrons from a metal surface when photons are incident on its surface

Question 4

Work function

Answer 4

The minimum energy required to release an electron from the surface of a metal

Question 5

Threshold frequency

Answer 5

The minimum frequency of e.m. radiation required to release electrons from the surface of a metal
Threshold frequency = work function / Planck constant

Question 6

Energy level

Answer 6

Discrete energy of an electron in an atom

Question 7

Continuous spectrum

Answer 7

All frequency are present in the spectrum

Question 8

Line spectrum

Answer 8

A series of bright lines against a dark background produced by light emitted by excited atoms

Question 9

Absorption spectrum

Answer 9

A series of dark lines within a continuous spectrum

Question 10

Photon

Answer 10

A quantum of energy of electromagnetic radiation