AKS 11 Review

AKS 11 Review

Electromagnetic Spectrum and Visible Light

Comparing mechanical & EM Waves

• Mechanical must have a medium, EM can travel through a vacuum

• ALL electromagnetic waves are transferse waves

• Both waves transfer energy and not matter

Effect of medium on wave speed

• Mechanical - as density increases, the speed of the wave increases (Fastest through solid, then liquid, slowest in gas)

• EM Waves - as density increases, the speed of the wave decreases (Fastest through vacuum, then gas, then liquid, then solid)

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Multiple Choice

Light waves are categorized as

• mechanical & transverse

• mechanical & longitudinal

• electromagnetic & transverse

• electromagnetic & longitudinal

Multiple Choice

A type of wave that is NOT capable of transmitting its energy through a vacuum.

• A. transverse

• B. longitudinal

• C. mechanical

• D. electromagnetic

Multiple Choice

Through which medium would a mechanical wave travel fastest?

• Vacuum

• Gas (air)

• Liquid (water)

• Solid (glass)

Multiple Choice

Through which medium would an electromagnetic wave travel fastest?

• Vacuum

• Gas (air)

• Liquid (water)

• Solid (glass)

Electromagnetic spectrum

• Energy is related to the frequency of the wave

Multiple Choice

Which kind of wave has the greatest frequency?

• gamma rays

• infrared

• ultraviolet

• microwaves

Multiple Choice

As the frequency of an electromagnetic wave increases, its energy _____.

• increases.

• decreases.

Visible Light

The part of the spectrum we can see.

Color is determined by the wavelength of the wave.

Red light has a long wavelength, low frequency, and low energy. Violet light has a short wavelength, high frequency, and high energy.

What is white light?

• Natural white light (from the sun) is not a single color but instead contains all colors of the visible spectrum

• A prism can be used to disperse a single beam of white light into the rainbow

• White can also be made by combining the primary colors of light

Color Mixing

• The three primary colors of light are RED, BLUE, and GREEN

• By mixing two primary colors you get the secondary colors - yellow, magenta, and cyan

• All 3 primary colors gives white

• All 3 secondary colors is black

Absorption and Reflection

• Objects appear as different colors because of the wavelengths of light that are reflected or absorbed

• We see the reflected wavelengths and that determine the color

• White reflects all and black absorbs all wavelengths

Multiple Choice

White light from the sun is made of all wavelenghts of visible light (ROY G BIV)

• True

• False

Multiple Choice

What color of light do you get by combining red, green, and blue light?

• Black Light

• White Light

• Ultraviolet Light

• Infrared Light

Multiple Choice

What color is produced when mixing cyan, yellow, and magenta inks (pigments).

• White

• Black

• Blue

• Green

Multiple Choice

Why does an apple look red?

• because it absorbs red light and reflects white light

• because it absorbs red light waves and reflects the others

• because it absorbs all colors of light

• because it reflects red light waves and absorbs the others

Index of Refraction

• Light slows down as it goes through more dense mediums

• A material's index of refraction determines how much light slows (higher index of refraction = slower)

Index of Refraction

• This equation can be used to determine the index of refraction (n) or the speed of light in a medium (v)

• C is the maximum speed of light (3x10⁸ m/s)

What is the index of refraction if the speed of light in a sugar solution is 2.01x10⁸ m/s? (C=3x10⁸ m/s)

What is the speed of light through a material if the index of refraction is 1.81? (C=3x10⁸ m/s)

Snell's Law

• Uses the angle of light and its refracted angle to determine the index of refraction for a material

• As light goes from one medium to another its speed changes and it bends

Light hits an emerald at an angle of 29^o and refracts to 17^o. What is the index of refraction?

Multiple Choice

What is the speed of light in a material that has an index of refraction of 1.88?

• 3.0 x 10⁸ m/s

• 1.88 x 10⁸ m/s

• 1.6 x 10⁸ m/s

• 5.64 x 10⁸ m/s

Multiple Choice

If light travels through a piece of glass at 2.1 x 10⁸ m/s, what is the index of refraction of the glass?

• 1.14

• 1.43

• 2.10

• 6.3

Multiple Choice

Light travels from air (n = 1.00) into a "mystery" material. The incident ray of light hits the surface at angle of 43^o and the refracted ray enters the mystery material at an angle of 27^o. What is the index of refraction of the mystery material? n₁sin(Θ₁) = n₂sin(Θ₂)

• 1.5

• 1.0

• 0.67

• 2.1