Electromagnetic waves

ELECTROMAGNETIC WAVES

Presented to:Dr. Hazrat Bilal Malakandi, PT

Group 1A Member (3rd semester DPT, Medical Physics)

Rabia NaeemHuma InayatSidrah ShinwariNajla Amar Iqra Ayub

Electromagnetic Waves

• If you have ever tuned in to listen to a radio ,a spoken headphone , turned on a light ,hand on X ray taken, felt the warmth of the sun on your skin.

• You have experienced ELECTROMAGNETIC WAVE.

Definition • “Electromagnetic waves are waves

which can travel through the vacuum of outer space .

• Electromagnetic waves are formed when an electric field couples with a magnetic field.

• The magnetic and electric fields of an electromagnetic waves are perpendicular to each other and to the direction of waves.”

How do moving charges create magnetic fields?• Any moving electric charge is surrounded by

an electric field and a magnetic field.

Production of 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

What is the speed of EM waves?

• All EM waves travel 300,000 km/sec in space. (speed of light-nature’s limit!)

• EM waves usually travel slowest in solids and fastest in gases.

Properties of electromagnetic wave

1. All are electromagnetic waves are transverse

2. They do not required any medium to travel though .

3. They travel at speed of 3 multiple by 10 -8 in vacuum.

4. They can all be reflected and refracted.5. They can all be emitted and absorb by

matter.

Graphically Representation

Electro Spectrum “Frequencies is called the

electromagnetic spectrum.”

• Different parts interacts with matter in different way

• As wavelength decreases, frequency increases…

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

Chart of wave length and frequency

Electromagnetic spectrum

• Includes following types of waves :

• Radio waves • Microwaves• Infrared waves• Visible light• Ultraviolet • X rays• Gamma rays

Region Frequency

Wavelength

Energy

Radio waves < 109

> 0.3 < 7x 10-7

Microwaves 109 - 3x1011

0.001 - 0.37x10-7 - 2x10-4

Infrared 3x1011 - 3.9x1014

7.6x10-7 - 0.001

2x10-4 - 0.3

Visible 3.9x1014 - 7.9x1014

3.8x10-7 - 7.6x10-7 0.3 - 0.5

Ultraviolet 7.9x1014 - 3.4x1016

8x10-9 - 3.8x10-7

0.5 - 20

X-rays 3.4x1016 - 5x1019

6x10-12 - 8x10-9

20 - 3x10 4

Gamma rays > 5x1019 < 6x10-12 > 3x104

Radio waves • Radio waves have the longest

wavelengths of all the electromagnetic waves.

• Low frequency.• Radio waves are often used to

transmit data and have been used for all sorts of applications including radio, satellites, radar, and computer networks.

Radio waves are used in medicine

• Is used to produce images of soft tissues, fluid, fat and bone.

Example : MRI and RFA.

• DIAGNOSE MANY PROBLEMS.Example : helps identify tumors.

• Radiofrequency Ablation (RFA)

uses heat to destroy cancer cells.

Microwaves • Microwaves are radio waves

with wavelengths less than 30 cm and higher frequency & shorter wavelength

• Cell phones and satellites use microwaves between 1 cm & 20 cm for communication

• Microwaves are useful in communication because they can penetrate clouds, smoke, and light rain.

• Microwave also in radar that helps to predict the weather.

Microwave waves are used in medicine

• Hyperthermia therapy is a type of medical treatment.

• Microwave ablation: used in treatment of liver tumor

• Microwave diathermy: used in pain management

• Transurethral microwave : thermotherapy used in treatment of lower urinary tract syndrome

 Infrared waves:

• Infrared waves are sometimes classified as "near" infrared or "far" infrared

• Between microwaves and visible light are infrared waves.

• Can be detected by heat and used in heat lamp.

• Higher energy then microwave and lower the visible light.

• Used daily in remote controls, to read CD-ROMs

Precautions• Strong infrared radiation in

certain industry high-heat settings may be hazard to the eyes, resulting in damage or blindness to the user.

• Since the radiation is invisible, special IR-proof goggles must be worn in such places

Modalities use

• Infrared lamps

• Digital infrared camera

Infrared Imaging in Medicine

• Oncology • Vascular disorders• Respiratory disorders• Skeletal • neuromuscular

diseases• Surgery• Tissue viability

Visible light

• This is the range of wavelengths from 390 to 700 nm which corresponds to the frequencies 430-790 THz.

• The portion of the electromagnetic spectrum that human eyes can detect.

•

You see different wavelengths as colors.

Blue has shortestRed is the longestLight looks white if all colors are present

Visible light use in medicines

• Visible light is also used in Scanning laser ophthalmoscope.

• In Endoscopy/ Keyhole Surgery

Ultraviolet Waves

• Ultraviolet waves have the next shortest wavelength after visible light.

• EM waves with wavelengths from about 400 billionths to 10 billionths of a meter.

• Used in tanning beds and sterilizing equipments.

Ultraviolet Waves use in medicines

• Have enough energy to enter skin cells

• Longer wavelengths – UVA• Shorter wavelengths – UVB

rays• Both can cause skin cancer

• Ultraviolet light is used in treatment of Psoriasis and Vitiligo

• Pregnancy• Abnormalities in the heart

and blood vessels• Organs in the pelvis and

abdomen• Symptoms of pain, swelling

and infection

Can UV radiation be useful

• Helps body make vitamin D for healthy bones and teeth

• Used to sterilize medical supplies & equip

• Detectives use fluorescent powder (absorbs UV & glows) to find fingerprints

X Rays • High wave energy • Used in : Medicines Industry Transportation

• To much exposure can damage the living tissue or even cause cancer

X rays use in medicines

• X-rays play an important role in dentistry and orthopedic investigation.

• They can penetrate soft tissue like skin and muscle.

• Are used to take X-ray pictures of bones in medicine.

Gamma rays • Gamma rays the highest

energy electromagnetic waves

• The actually come from radioactive elements or stars

• Inspection tools in industry

Gamma rays use in medicines

Positron Emission Tomography (PET) is a nuclear medical imaging tool which used gamma rays.

• Example :• Neurological diseases such

as Alzheimer’s and Multiple Sclerosis

• Effectiveness of treatments

• Heart conditions• Gamma Knife uses beams

of highly focused gamma rays to treat tumors or other abnormalities in the brain.

• Gamma rays can check how far a cancer has spread and how well treatment is working.

What question do you have?