Electromagnetic Waves

1. Electromagnetic Waves

2. Light is a phenomenon known as electromagnetic waves. • Oscillating electric and magnetic fields create electromagnetic waves. • We’ve learned that a changing magnetic field can induce a current in a circuit (Faraday’s law of induction) • Coulomb’s law which describes the electrostatic force between two charges. • Ampere’s law which states that a magnetic field is created around a current carrying wire

3. Electromagnetic waves are simply oscillating electric and magnetic fields where the they move at right angles to each other and also at right angles to the direction the wave is moving.

5. The electric field oscillates back and forth in one plane while magnetic field oscillates back and forth in a perpendicular plane and the wave travels in the direction that is perpendicular to both of the oscillating fields those kinds of wave are called transverse waves.

6. Electromagnetic waves consist of changing electric and magnetic fields. • Scottish physicist James Clerk Maxwell created a simple yet sophisticated set of equations to describe the relationship between electric and magnetic fields

7. Maxwell believed that nature is symmetric and he hypothesized that a changing electric field should produce a magnetic field in a manner analogous to Faraday’s law of induction. • Maxwell’s equation predicted that a changing magnetic field would create a changing electric field which would in return create a changing magnetic field. Predicted result = A wave that moves through space at the speed of light

9. A German physicist named Heinrich Hertz generated and detected electromagnetic waves in his laboratory which were a confirmation of Maxwell’s work.

10. Maxwell

11. Electric and magnetic forces are aspects of a single force called electromagnetic force

12. The four fundamental forces in the universe are: • Strong force (holds together the nucleus of an atom) • Electromagnetic force • Weak force (Nuclear decay) • Gravitational force

13. Electromagnetic and weak force are two aspects of a single electroweak interaction. • The electromagnetic force obeys the inverse square law. The force’s magnitude decreases as one over the distance from the source squared. • The inverse square law applies to phenomena such as gravity, light and sound that spread equally in all directions and with infinite range

14. All electromagnetic waves are produced by accelerating charges. • Changing electric field induces a magnetic field perpendicular to the electric field. The wave propagates itself as each changing field induces the other

15. Frequency of oscillation determines frequency of wave produced. • In an antenna, two metal rods are connected to an alternating voltage that is changed from positive to negative voltage. • The wave length of the wave is related to the frequency f • Equation

16. Electromagnetic waves transfer energy. • All types of waves whether they are mechanical or electromagnetic or are longitudinal or transverse have an energy associated with their motion. • The transfer of energy associated with an electric and magnetic field is called electromagnetic radiation • Varies periodically and travels at the speed of light.

17. The energy carried by electromagnetic waves can be transferred to objects in the path of the waves or converted to other forms such as heat. • Eg: Energy from microwave radiation to warm food • Energy from the sun reaches Earth via electromagnetic radiation across a variety of wave lengths like Radio, Infrared, Visible, Ultraviolet, Extreme UV & X-ray.

19. K thanks bye.