# Spectroscopy and Electromagnetic Spectrum – Instrumental Methods of Analysis B. Pharma 7th Semester

Spectroscopy and Electromagnetic Spectrum

Session Objectives

By the end of this
session, students will be able to:

Ø  Explain
the salient features of Electro Magnetic Spectrum

Ø  Outline
the parameters for identification and distinction of different Electromagnetic

Spectroscopy

Spectroscopy
is the study of the way light (electromagnetic radiation) and matter interact.

There
are a number of different types of spectroscopic techniques

The
basic principle is to pass a beam of a particular electromagnetic radiation
through a sample and observe how it responds to such a stimulus; allowing
scientists to obtain information about the structure and properties of matter.

Electromagnetic

Electromagnetic
Spectrum

The electromagnetic spectrum comprises of waves of

The systematic display of whole range of EM wave frequencies
is called the electromagnetic spectrum.

Different parts interact with matter in different ways.

The frequencies humans can see are called visible light, a
small part of the whole spectrum.

Visible light

 Color Wavelength Violet 400-420 nm Indigo 420-440 nm Blue 440-490 nm Green 490-570 nm Yellow 570-585 nm Orange 585-620 nm Red 620-780 nm

What are
electromagnetic waves?

How
electromagnetic waves are formed

How
electric charges produce electromagnetic waves

Properties
of electromagnetic waves

Electromagnetic
Waves…

Do
not need matter to transfer energy.

Are
made by vibrating electric charges and can travel through space by transferring
energy between vibrating electric and magnetic fields.

How do moving charges
create magnetic fields?

Any
moving electric charge is surrounded by an electric field and a magnetic field.

What happens when
electric and magnetic fields change?

A
changing magnetic field creates a changing electric field.

One
example of this is a transformer which transfers electric energy from one
circuit to another circuit.

In
the main coil changing electric current produces a changing magnetic field

Which
then creates a changing electric field in another coil producing an electric
current

The
reverse is also true.

Making
Electromagnetic Waves

When
an electric charge vibrates, the electric field around it changes creating a
changing magnetic field.

The
magnetic and electric fields create each other again and again.

An
EM wave travels in all directions.  The
figure only shows a wave traveling in one direction.

The
electric and magnetic fields vibrate at right angles to the direction the wave
travels so it is a transverse wave.

SUMMARY

Spectroscopy
is the study of the way light (electromagnetic radiation) and matter interact.

The
systematic display of whole range of EM wave frequencies is called the electromagnetic
spectrum

Electromagnetic