radiant energy or electromagnetic energy (em)

Radiant Energy or Electromagnetic Energy (EM)

• All radiant energy travels at 3.0 x 108 m/sec in space

• Velocity of a wave = wavelength x frequency • Visible light is just one type of EM Energy

Electromagnetic Spectrum

Radiation comes in the form of vibrating or “throbbing bundles of energy” called photons The frequency of the

vibrating electric charges determines which type and how muchenergy will be given off

All of the forms of radiation given off All of the forms of radiation given off by vibrating electric chargesby vibrating electric charges

The entire E.M. Spectrum in order from lowest to highest

frequency• Radio waves: AM and

FM• Microwaves: cooking• Infrared: heat• Visible: (ROYGBV)• Ultraviolet: tanning• Xrays: medical• Gamma:

Waves - Energy carried by rhythmic disturbances

• Two types:• 1. E.M. radiation

move through empty space

• 2. Mechanical require a medium (air, water or any type of matter) for movement

Waves - 2 Types

All waves have similar properties

• Frequency- the number of vibrations per second or the speed of the movement of the vibrating particles

• Amplitude – the size of the movement of the vibrating particles

• Both are controlled by the disturbance that created the waves

Velocity of all waves - v=f λ

f-frequency and λ is wavelength (distance between identical points on two consecutive waves)

Reflection- bounce off barriers in regular ways

Refraction- waves can change direction when speed changes

And the answer is?

38 At 0°C sound travels through air at a speed of 330 m/s. If a sound wave is produced with a wavelength of 0.10 m, what is the wave’s frequency?

F 0.0033 HzG 33 HzH 330 HzJ 3300 Hz

Use the formula chart!!!

Velocity = f λ OR f λ OR

330 m/s = f x 0.10 m330 m/s = f x 0.10 m

JJ 3300 Hz 3300 Hz

Transverse Waves

• In Transverse Waves particles vibrate at right angles to the direction the wave travels.• Ex. E. M. Waves,

waves on a slinky or rope coil, ocean waves

Longitudinal or Compress ional Waves

Vibrating particles move back and forth along the direction of the wave velocity

Parts consist of compressions and rarefactions

Ex. Sound Waves

Sound Waves are Compression Waves

Sound is produced when a compression is made.

It requires a producer and a medium to travel through.

The more elastic the object, the faster sound travels.

Sound acts like other waves

• Echoes are reflected sound waves

• Sonar uses echoes to judge distance to obstructions

• Human hearing is 20-20,000 Hz, below 10 Hz is infrasonic, and above 20,000 Hz is ultrasonic.

Sound Waves move through matter not through empty space.

32 One tuning fork is struck and placed next to an identical fork. The two forks do not touch. The second tuning fork starts to vibrate because of —

F interferenceG the Doppler effectH resonanceJ standing waves

Resonance is the vibration of another object struck by a wave of the correct frequency. Since the forks are identical, the second one receives the correct frequency to begin vibrating.