Semiconductors :    Substances whose conductivities lie between insulators and metals

Annealing          :   The process of cooling metals very slowly in order to toughen or temper

Photoelectric devices :    Devices which produce electricity when struck by light beams

AC :  Alternating  Current

DC :  Direct Current

Centripetal Acceleration : Acceleration tending towards the centre

Kinetic Energy : Energy possessed by a moving body because of its motion

Potential Energy : Energy possessed by a stationary body by virtue of its position

Electromagnetic Theory :Theory behind magnetic effects of  electric current

Angular velocity  :Velocity of a body moving through an angle

Postulate : Put forward as a basis for reasoning

Angular Momentum :Momentum gained by a body moving through an angle

Joules :  Unit of energy or work

Spectral Lines :Spectra of a ray of light

Spectroscopic : By means of an instrument for producing and examining the spectra of a ray of light

Photon : A packet of light

Valence Electrons : Electrons in the outermost shell of an atom. Decides the stability of the atom of the metal

Shell : Virtual container for orbiting electrons

Vacuum Tubes :Devices which were used in amplifier circuits employing principles of thermionic emission

Crystalline Structure :Structure in which the atoms are arranged in a regualr order

Covalent Bond :A bond whereby two atoms share each other's electrons to attain stability

Recombinations : Combining of  holes and electrons neutralising each other's charges.

Thermal Equilibrium :The state of existence where there is no transfer of temperature

Alloy : Mixture of Metals ,usually a lower metal  with a higher metal

n-type substrate  :n-type base material

Transverse : Placed across

Abscissa :The x axis of a coordinate system

Distortion :Out of usual shape.

Quiescent :Rest,motionless,passive.

Cascade Amplifiers:Amplifier setup  in which output of the first amplifier becomes the input to the second amplifier and so on.

Microwave : Very short wave as used in Radio / Radar

Harmonics:  Waves of different frequencies

Amplitude : Largeness or breadth of the wave

Decibel : Unit for measuring the relative loudness of sounds