Basics of Spectroscopy
Spectroscopy deals with the study of interaction of electromagnetic radiation with matter. Electromagnetic radiation is a simple harmonic wave of electric and magnetic fields fluctuating orthogonal to each other (Figure 3.1A).
Figure 3.1: An electromagnetic wave showing orthogonal electric and magnetic components (A); a sine wave (B); and uniform circular motion representation of the sine function (C).
A simple harmonic function can be represented by a sine wave (Figure 3.1B):
Sine wave is a periodic function and can be described in terms of the circular motion (Figure 3.1C). The value of y at any point is simply the projection of vector A on the y-axis, which is nothing but A sin θ . Equation (1) can therefore be written in terms of angular velocity, ω.
where, z = displacement in time t and c is the velocity of the electromagnetic wave
If the wave completes ν cycles/s and the wave is travelling with a velocity c metres/ sec, then the wavelength of the wave must be 
metres.
