15.2

Electromagnetic waves need no medium, are produced by moving electrons in a field.

Can be reflected, refracted, diffracted, produce standing waves

Tiny bundles of energy that produce light.

They increase as frequency increases and wavelengths decrease

Sound and Light

4

Absorbs Energy

Light is the fastest wave in the universe

Speed of light is 300 million m/sec- it takes 8 minutes from sun to earth

Affected by the material that it passes through

Transparent- air, water, glass Translucent- frosted glass diffuses light

Opaque-light can’t pass through.

If light travels through an object it is =transparent

If light is blocked by an object and a dark shadow is cast it is= opaque.

If some light passes through but not all and a light shadow is present it is=translucent.

*AIMS:Primarily Physics: Just Passing Through Activity

Quantity of amount of light illuminating a surface, dependant on amount of light.

Decreases with distance

Sound and Light

10

Describes physical waves using amplitude, wavelength and frequency.

Arranged by Frequency and wavelength

Left side of spectrum has low frequency and large wavelengths, right side has high frequency and close wavelengths

You begin with radio wave, microwaves, infrared, visible light, ultraviolet, x-rays and gamma

Radio- lowest frequency, longest wavelength. Includes AM/FM and radar

Radar- Radio Detecting and Ranging

Radar uses short radio impulses to locate and monitor speed once the signal is reflected back.

Microwaves follow radio waves and are used in cooking/communication

Infrared- slightly lower wavelength than visible light

Felt has heat like in the sun and warming lamps

Visible light – color spectrum

ROY G BIV Red, orange, yellow, green, blue, indigo ,violet

The colors are ordered by wavelength.

50% of the sun’s light is visible

Ultraviolet- higher frequency than visible light

Kills bacteria, causes cancer, produces vitamin D

X-rays- frequency above ultraviolet waves, passes trough skin but is absorbed by bone, Lead can absorb all X-rays

Gamma rays- has highest frequency and shortest wavelength, has highest energy and can penetrate 3 meters of concrete.