Name ______________________________Date __________________ Period ______

Light NotesElectromagnetic Waves

Electromagnetic Waves consist of oscillating ______________ and _______________ fields, which radiate outward from the source at the speed of light (_______________________)

All electromagnetic waves, including visible light, travel at the speed of light (c) in a _______________.

c = 3.00 x 108 m/s

Although the speed of all EM waves is the same, waves have different wavelengths and frequencies

Formula: c = fλ

Relationship:

Practice: The AM radio band extends from 5.4 x105 Hz to 1.7 x106 Hz. What are the longest and shortest wavelengths in this frequency range?

Practice: If an electromagnetic wave has a frequency of 7.57 x1014 Hz, what is its wavelength? What part of the spectrum does this wave belong to?

Refraction

Refraction is the ______________________ as the light passes between two substances in which the _________ of the wave differs.

Light moves at different ___________ in different materials due to a difference in the mediums _____________. When light moves from _______ speed to ______ speed(Ex: air to glass), the ray is bent __________ the normal When light moves from _____ speed to ______ speed (Ex: glass to air), the ray is bent ______ from the normal

Name ______________________________Date __________________ Period ______

Law of Reflection

Law of Refraction

Every medium has a measured _________________________________. Values of common substances are found on your blue sheet.

index of refraction= speed of light∈avacuumspeed of light∈medium

n= cv

The _________________ the n value, the ____________ light moves in that medium.o the ________________ increases, but the ___________________ stays the same.

Snell’s Law

n1 sin θ1¿ n2sin θ2

n1=index of refraction for firstmedium

θ1=angle of incidence

n2=index of refraction for the secondmedium

θ2=angle of refraction

n1 v1 ¿n2 v2

v1=speed of light∈ firstmedium

v1=speed of light∈secondmedium

Total Internal Reflection

Total Internal Reflection: _______________________________________________________________ Critical Angle: the ___________________________ at which the refracted light makes an angle of _______ with

the normal.

Name ______________________________Date __________________ Period ______

Practice: A certain gas has an index of refraction of 1.23. What is the speed of light in the gas?

Practice: A light ray of wavelength 589 nm (produced by a sodium lamp) traveling through air strikes a smooth, flat slab of crown glass at an angle of 30.0˚ to the normal. Find the angles of refraction.

Practice: Find the critical angle for a water-air boundary if the index of refraction of water is 1.33.