Electromagnetism

1. Topic : “electromagnetism”
PREPARED BY :
 Kundan Parmar

2. Introduction
Magnetic field lines
Direction of Magnetic field
Electromagnet
Tesla Coil
The Electromagnetic Spectrum
ELF-EMF may affect the DNA in Human cells
Example of Electromagnetic Radiation
Uses of Electromagnetic Waves

3.  Electricity and magnetism are different facets of
Electromagnetism.
Introduction
• A moving electric charge produces magnetic field.
• Changing magnetic fields move electric charges
 This connection first elucidated by Faraday, Maxwell.
 Einstein saw electricity and magnetism as frame
dependent facets of unified Electromagnetic force.

4. Magnetic field lines
 The magnets exert their influence in the surroundings, this is called
magnet field.
 Magnetic field is a quantity that has both direction and magnitude.
 The direction of the magnetic field is taken to be the direction in
which a north pole of the compass needle moves inside it.

5. Direction of Magnetic field
(1) Right hand-palm rule :
“First make the thumb and fingers of the right hand
perpendicular to each other and put the thumb along the wire in
the direction of the current and fingers point towards the point
of observation.”

6. (2) Right hand-thumb rule :
“If the thumb is along the direction of current,
wrapped fingers will show the direction of circular
magnetic field lines.”

7. (3) Fleming Left-hand rule :
“Hold out your left hand with forefinger, second finger and
thumb at right angle to one another. If the fore finger
represents the direction of the field and the second finger that
of the current, then thumb gives the direction of the force.”

8. (4) Right hand rule :
“Hold out the right hand with the first finger, second and
thumb at right angle to each other. If finger represent the
direction of the line of force, the thumb points in the direction
of motion or applied force, then second finger point in the
direction of the induced current.”

9. (5) Magnetic field in a circular loop :
Clockwise : South pole Anticlockwise : North pole

10. Electromagnet
 Arranging wire in coil and running a current through
produces a magnetic field that looks a lot like bar
magnet.
• Called an electromagnet
• Putting a real magnet inside, can shove the magnet back and
forth depending on current direction : Solenoid

11. Tesla Coil
 A Tesla coil is a resonant air core transformer system
inventor Nikola Tesla in the 1890’s.
 Originally, Tesla coils were designed to broadcast electricity
and signals wirelessly.
 It is a from of induction coil for producing highfrequency
alternating currents.

12. The Electromagnetic Spectrum
 Relationship between frequency, speed and wavelength,
frequency × wavelength =speed of light
 Different frequencies of electromagnet radiation are better
suited to different purposes.
 The frequency of a radio wave determines its propagation
characteristics through various media.
 Photon energy is directly proportional to the wave frequency,
so gamma ray photons have very low energy.

13. ELF-EMF may affect the DNA in Human cells
 Used technical to detect any DNA damage at the level of the
individual eukaryotic cell (Comet assay).
 Human primary fibroblast cells were exposed to 50Hz of emf at 1
militesla (mT) of flux density.
 Assay showed that the processes of DNA replication and cell
reproduction were the ones affected, not on the
DNA it self.
 In conclusion, the exposure of human primary fibroblast to
ELF-EMF simulates cell termination (necrosis) rather than
DNA alteration (Focke et al. 2009)

14. Example of Electromagnetic Radiation
 AM and FM radio waves
 Cell phone communication links
 Microwaves
 Infrared radiation
 Light X-rays
 Gamma rays

15. Uses of Electromagnetic Waves
 Communication system
(One way and two way)
 Radar
 Cooking (Microwaves)
 Medical Imaging (X rays)
 “NIGHT VISION” (Infrared)
 Astronomy (Radio, Microwave, IR, Visible, UV, Gamma)