The document discusses the electromagnetic spectrum, which includes different types of electromagnetic waves arranged by increasing or decreasing frequency and wavelength. It lists the different regions of the electromagnetic spectrum, including gamma rays, x-rays, ultraviolet radiation, visible light, infrared radiation, microwaves, and radio waves. Each region is characterized by its frequency and wavelength. The document also discusses the properties shared by all electromagnetic waves and provides examples of calculating beat frequency.

1. WAVES Cont...
ELECTROMAGNETIC SPECTRUM
The electromagnetic spectrum isa continuousband of all electromagnetic
waves arranged inorder increasing or decreasing frequenciesor wavelength
change.
The electromagnetic spectrum includeswavelength such as;
1. Visiblelight
2. Infrared radiations
3. Radiowaves
4. Ultraviolet radiations
5. X – rays
6. Gamma rays
7. Microwavesetc
NB: All the transversewaves traveling at the speed of 3 x 108ms-1 and can
travel through vacuum arethemembersof the electromagneticspectrum.
These waves are characterized bydifferent frequencyand wavelength.
The electromagnetic spectrum canbedivided intoseven major regionor
bands
Table1.0 The electromagneticspectrum
GAMMA RAYS (γ-rays)

2.  Gamma raysarethe rays which have short wave length and high
frequency. Gammarayscanbe used to kill dangerouscell in
humansbut careis needed in their use, becausethey also attackand
kill healthycells. The gamma rayscanbe detected by Geiger Miller
Tube (G-Tube) and photographic plates or film
X - RAYS
 X–Rays areproduced when fast moving electronsare stopped by a
metaltarget. X-Raysareused in Radiology (isthe scienceof
applying x-raysto medicinetoproducepicturesof internalorgansin
the body). They are also used to kill dangerouscells and tumors
(abnormality) inthebody it should be noted that healthycell is also
killed when thex- rays are used. They canbe detected by
photographic plates.
ULTRA VIOLET RADIATIONS (U V)
 Ultra violet radiationsarejust beyond the violet of the visible
spectrum. Theyhave longer wavelength thanthose of x-rays. UV
radiationsprovidevitaminDfrom the sun. Excessive UV radiation
canbe harmfulto the eyes and skin (recall albino). They are also used
to detect forged bank notes.
VISIBLE SPECTRUM
 Visiblespectrum isa narrow band of radiationof wavelength from
pad to violet. The visible spectrum canbe detected by humaneye,
light dependent resistor (LDR) such as photoelectric cell(solar cell
and solar panels)
ROYGBIV
Where;
R=red
O=orange
Y=yellow
G=green

3. B=blue
I=indigo
V=violet
INFRARED SPECTRUM
 Infrared radiationisa band of radiationscharacterized bywarmth.
These heat radiationsareproduced from hot bodies such as, electric
fires. The infra red radiationscanbe detected by thermophileand
thermometer. Allbodiesemit infra red radiations.
MICROWAVES
1. The microwavesareproduced bythe oscillationof charges. Theseare
used in cooking (oven) and in telecommunication, thebeamsof
microwavescarrymuch moreinformationthat telephonewires.
2. Huge concavedishes are used to send and receive microwavesignals.
3. The microwavearealso used in the operationof RADAR (Radio
waves detect and Ranging) and in TV waves
RADIO WAVES
1. Radiowaves are produced by electricaloscillationsinthe circuit.
They are used for communicationpurposes.
NB: Lightning also produceradiowaves. That is why radio
programmerscracklewhenthere is a thunderstorm. Theradiowaves
have the longest wavelength.
Properties ofelectromagnetic spectrum
All forms of electromagneticradiationhavethe following properties;
1. They are all transverse waves traveling infree spaceat 3 x108m/s.
2. They can be refracted , diffracted and exhibit thephenomena if
interference.
3. They do not need materialmedia for travel, they caneven pass
through vacuum.
4. They carryno electric charge.

4. 5. They obey wave equation, c=fλ
6. They transfer energy from a sourceto a receiver in the form of
oscillating electric and magneticfield.
BEAT FREQUENCY
 Beat frequencyis a regular riseor fall of sound waves which have
nearly equal frequencies.
The beat frequencyor the number of beatsis givenas the difference
betweentwo frequenciesof sound.
Beat frequency= f1 - f2 or f2 - f1
Beat frequency = | f2 — f1|
Examples
1. Two sounds are emitted at thesametimewith frequencies512Hz and
518Hz. Calculatethe beat frequency.
Solution
from; | f2 — f1 |
Beat frequency = |518 — 512|
= |6|
= 6Hz
2. Given that thebeat frequencyis 4Hz. One of the sound waves has a
frequencyof 20Hz. Calculatethepossible values of the frequenciesof
the other sound wave.
Let the frequenciesbe f1 and f2
Beat frequency = | f2 — f1 |

5. 4Hz = |f2 — 20Hz|
4Hz = f2 —20Hz
4Hz + 20Hz = f2
24Hz = f2
f2 = 24Hz
4 = — |f2 —20Hz|
4 = — f2 +20Hz
4—20Hz = —f2
—16Hz = —f2
f2 = 16Hz
The possible values are 24Hz and 16Hz
Question
A 256Hz turning workproducessound at the sametimewith a, 249Hz.
What isthe beat frequency?
Ans: 7Hz