Section 2

The Nature of Light

Notebook # 6

1. Visible light is composed of waves that have several different wavelengths. What happens to light that passes through a prism?

2. Why do we see rainbows on rainy days?

3. An airplane can be detected by radar. When radio waves strike an airplane, they are reflected back to a detector and the airplane shows up on a radar screen. Explain how stealth airplanes fly through the air without being detected by radar.

Bellringer: Section 2

I. Waves and Particles

A. Light – a transverse wave that does not need a medium.

1. Light is also electromagnetic waves.

B. Light – a packet of energy.

1. called a photon.

C. Both models are acceptable to scientists.

D. Frequency & energy are proportional.

1. As frequency increases, so does energy.

E. Speed of light depends on:

1. The medium in which it is traveling.

i. Fastest in a vacuum.

ii. c = 3.0 x 108 m/s

II. The Electromagnetic Spectrum

A. Electromagnetic waves – waves created byvibrating electric charges.

1. Electromagnetic waves are made when an electric charge moves back and forth.

2. When an electric charge vibrates, the electric field around it vibrates.

3. This also causes the magnetic field to vibrate.

B. The range of electromagnetic wave frequencies is known as the Electromagnetic Spectrum

Radio waves

Microwaves Infrared Optical Ultraviolet X-Rays Gamma rays

Low to high Frequency

Long to short

C. Radio Waves - long , low frequency. Low photon energy.

1. Used in communications and cordless telephones.

D. Microwaves - used in cooking food and communications (cell phone signals)

E. Infrared radiation - generally associated with heat.

1. Used to keep food warm & produce heat images.

F. Visible Radiation - only part we can see.

ROY G BIV

G. Ultraviolet Radiation – used in hospitals to kill bacteria.

ed range

ellow

reen

lue ndigo

iolet

H. Gamma & X-Rays - high energy.

1. Gamma rays can be used to destroy cancer cells.

Section 2 review

Pg. 505

Questions 1 – 5

Write answers & questions