Electromagnetic Spectrum Flashcards
What is the Electromagnetic Spectrum?
The continuum of electromagnetic radiation
* As radiation energy DECREASES, wavelength INCREASES, frequency DECREASES
What is the wavelength range of Gamma waves?
0.0001 - 0.01 nm
What is the wavelength range of X-Ray waves?
0.1 - 10 nm
What is the wavelength range of UV waves?
10 - 400 nm
What is the wavelength range of Visible Light waves?
400 - 700 nm
What is the wavelength range of Infrared waves?
700 nm - 0.01 cm
What is the wavelength range of Radio waves?
1 cm - 100 m
What do the properties of electromagnetic radiation depend on?
- Amplitude (A)
- Wavelength (λ)
- Crest & Trough
- Speed of Light (c)
- Frequency (f)
- Period (T)
What is a Photon?
Light particle
What is the energy of a photon proportional to?
Energy of photon is proportional to the frequency of the radiation
What is the Amplitude (A) of a wave?
Height of wave
What is the Wavelength (λ) of a wave?
Distance between two crests of wave
What is the Crest and Trough of a wave?
Highest and lowest points of a wave
With respect to light waves, explain frequency (f) and period (T)
- Frequency (f) = number of waves that pass a fixed point per second
- Period (T) = number of seconds it takes for a wave to pass a fixed point
What is the speed of light (c)?
3.0 x 10^8 m/s
What is the relationship between c, f and λ?
λf = c
OR
f = cλ
Explain Planck’s constant and mention the value of the constant
- Planck’s Constant (h) links a wave’s frequency (f) to its total energy (E)
- Planck’s Constant (h) = 6.6262 x 10^-34 Js
What is the relationship between E, c, f, and λ?
- λf = c
- E = hf = hc/λ
What is the formula for the energy (E) of a photon?
E = hf
What is a Hz?
One wave cycle per second
What is an electron volt (eV)?
Energy required to move a single electron across a potential difference of 1V
How many joules are in an eV?
1eV = 1.602 x 10^-19 J
What is the approximate eV of gamma rays?
10^7
What is the approximate eV of visible light?
10
What is the approximate eV of radio waves?
10^-7
Which spectroscopy technique has a wavelength of 50cm?
a) UV
b) Visible
c) NMR
d) X-Ray
e) ESR
f) IR
c) NMR
Which spectroscopy technique has a wavelength of 0.5cm?
a) UV
b) Visible
c) NMR
d) X-Ray
e) ESR
f) IR
e) ESR
Which spectroscopy technique has a wavelength of 100µm?
a) UV
b) Visible
c) NMR
d) X-Ray
e) ESR
f) IR
f) IR
Which spectroscopy technique has a wavelength of 500nm?
a) UV
b) Visible
c) NMR
d) X-Ray
e) ESR
f) IR
b) Visible
Which spectroscopy technique has a wavelength of 30nm?
a) UV
b) Visible
c) NMR
d) X-Ray
e) ESR
f) IR
a) UV
Which spectroscopy technique has a wavelength of 1nm?
a) UV
b) Visible
c) NMR
d) X-Ray
e) ESR
f) IR
d) X-Ray
Explain the energy state of atoms and how an electron can move from ground state to a higher energy state
- Lowest energy state (ground state) of an atom has electrons filling orbitals with 2 electrons per orbital
- When energy is added, an electron can be promoted to a higher energy orbital
How does an excited state electron move back down to a lower energy level and what happens when it does?
Excited state electron can move back down to a lower energy level if it releases the energy difference as electromagnetic radiation
Explain how movement of an excited state electron back down to a lower energy level can be used to identify hydrogen in the atmosphere
If an excited state electron in hydrogen drops from n = 3 to n = 2, it releases electromagnetic radiation of wavelength 656.3 nm
Explain the difference between the absorption and the emission spectrum of hydrogen
Explain the relationship between photon energy level and absorption by hydrogen
What is the formula to calculate the energy of a photon?
E = hc/λ
If an electron absorbed 9.5eV of energy, what wavelength does this correspond to on the electromagnetic spectrum?
- E = 9.5 eV = (1.602 x 10^-19) x 9.5 eV = 1.522 x 10^-18 J
- 1.522 x 10^-18 J = hc/λ
- λ = hc/1.522 x 10^-18 J
- λ = (6.6262 x 10^-34 Js) x (3.0 x 10^8 m/s) / 1.522 x 10^-18 J
- λ = 1.31 x 10^-7 m
- λ = 130 nm
What range of wavelengths on the electromagnetic energy spectrum are radiated from the Sun?
10^2 - 10^5
What range of wavelengths on the electromagnetic energy spectrum are radiated from the human body?
10^4
What type of spectroscopy would detect the range of wavelengths radiated from the human body?
IR