Unit 7: Electromagnetic Radiation Flashcards
Wavelength
distance between crests
Crests
highest point of an electromagnetic wave
(POINT)
What is wavelength calculated in?
nm (nanometers)
nano = 10^-9
Frequency
number of waves that pass a given point in some unit of time
What units is frequency in?
waves/sec or Hertz (hz)
Amplitude
max height of wave
amplitude = 0
node
The electromagnetic spectrum…
arranges forms of _______ from _______ to ______
Energy, Low, High
The electromagnetic spectrum
Arranges _____ from _____ to ______ wavelengths.
Energy, Long, Short
The electromagnetic spectrum
Shows visible light with wavelengths from 700 (___)-400 (___) nm.
red, purple/violet
What color is at 700 nm?
red
What color is at 400 nm?
purple/violet
What color light has the lowest energy?
red light
What does an atomic spectrum consist of?
Lines of different colors formed when light from a heated element passes through a prism.
and
Photons emitted when electrons drop from high to lower energy levels.
What do heated metals emit?
electromagnetic Radiation with frequency that depend upon energy (temperature)
How did Planck explain the behavior of heated metals?
assumed vibrating atoms gave rise to electromagnetic radiation
Energy is proportional to the what of vibration?
frequency
Planck’s equation
E = h x frequency
h = 6.62 x 10^-34 Jxs
Photoelectric Effect
ejection of electrons when light strikes the surface of a metal
What must the frequency be for the photoelectric effect to occur?
frequency must be high enough
Light must act as a _______ in the photoelectric effect
particle (photon)
Why does light have to act as a particle (photon) in the photoelectric effect?
to bump into an atom to knock out an electron
λ
wavelength
wavelength symbol
λ
v
frequency
frequency symbol
v
As frequency increases, energy _____
increases
As wavelength decreases, energy ______
increases
Spectra
White light that passes through a prism and is separated into colors called a continuous spectrum
- gives the colors of the rainbow
How do electrons “jump” to a higher energy level?
an electron absorb energy
What energy level does an electron go through if it absorbs energy?
it “jumps” to a higher energy level
Excited State of an Atom
when an electron absorbs energy and “jumps” to a higher energy level
What does it mean when an electron falls to a lower energy level?
energy is emitted
When energy is emitted what energy level does the electron go to?
electron falls to a lower energy level
Ground State of an Atom
when everything is in balance
What does the emitted energy of an atom do and mean?
if in the visible range, it presents a color
when energy is emitted, one color of a light is also emitted
drops down to a lower energy level
Light Equation 1
v=f x λ
v=f x λ
velocity = frequency x wavelength
Velocity
3x10^8 m/s
Do you have to convert to m?
YES!
What relationship does frequency and wavelength have?
inverse relationship
node
when amplitude = 0
