Electromagnetic Spectrum

Question 1

What is the Electromagnetic Spectrum?

Answer 1

The continuum of electromagnetic radiation
* As radiation energy DECREASES, wavelength INCREASES, frequency DECREASES

Question 2

What is the wavelength range of Gamma waves?

Answer 2

0.0001 - 0.01 nm

Question 3

What is the wavelength range of X-Ray waves?

Answer 3

0.1 - 10 nm

Question 4

What is the wavelength range of UV waves?

Answer 4

10 - 400 nm

Question 5

What is the wavelength range of Visible Light waves?

Answer 5

400 - 700 nm

Question 6

What is the wavelength range of Infrared waves?

Answer 6

700 nm - 0.01 cm

Question 7

What is the wavelength range of Radio waves?

Answer 7

1 cm - 100 m

Question 8

What do the properties of electromagnetic radiation depend on?

Answer 8

• Amplitude (A)
• Wavelength (λ)
• Crest & Trough
• Speed of Light (c)
• Frequency (f)
• Period (T)

Question 9

What is a Photon?

Answer 9

Light particle

Question 10

What is the energy of a photon proportional to?

Answer 10

Energy of photon is proportional to the frequency of the radiation

Question 11

What is the Amplitude (A) of a wave?

Answer 11

Height of wave

Question 12

What is the Wavelength (λ) of a wave?

Answer 12

Distance between two crests of wave

Question 13

What is the Crest and Trough of a wave?

Answer 13

Highest and lowest points of a wave

Question 14

With respect to light waves, explain frequency (f) and period (T)

Answer 14

• 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

Question 15

What is the speed of light (c)?

Answer 15

3.0 x 10^8 m/s

Question 16

What is the relationship between c, f and λ?

Answer 16

λf = c
OR
f = cλ

Question 17

Explain Planck’s constant and mention the value of the constant

Answer 17

• 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

Question 18

What is the relationship between E, c, f, and λ?

Answer 18

• λf = c
• E = hf = hc/λ

Question 19

What is the formula for the energy (E) of a photon?

Answer 19

E = hf

Question 20

What is a Hz?

Answer 20

One wave cycle per second

Question 21

What is an electron volt (eV)?

Answer 21

Energy required to move a single electron across a potential difference of 1V

Question 22

How many joules are in an eV?

Answer 22

1eV = 1.602 x 10^-19 J

Question 23

What is the approximate eV of gamma rays?

Answer 23

10^7

Question 24

What is the approximate eV of visible light?

Answer 24

10

Question 25

What is the approximate eV of radio waves?

Answer 25

10^-7

Question 26

Which spectroscopy technique has a wavelength of 50cm? a) UV b) Visible c) NMR d) X-Ray e) ESR f) IR

Answer 26

c) NMR

Question 27

Which spectroscopy technique has a wavelength of 0.5cm? a) UV b) Visible c) NMR d) X-Ray e) ESR f) IR

Answer 27

e) ESR

Question 28

Which spectroscopy technique has a wavelength of 100µm? a) UV b) Visible c) NMR d) X-Ray e) ESR f) IR

Answer 28

f) IR

Question 29

Which spectroscopy technique has a wavelength of 500nm? a) UV b) Visible c) NMR d) X-Ray e) ESR f) IR

Answer 29

b) Visible

Question 30

Which spectroscopy technique has a wavelength of 30nm? a) UV b) Visible c) NMR d) X-Ray e) ESR f) IR

Answer 30

a) UV

Question 31

Which spectroscopy technique has a wavelength of 1nm? a) UV b) Visible c) NMR d) X-Ray e) ESR f) IR

Answer 31

d) X-Ray

Question 32

Explain the energy state of atoms and how an electron can move from ground state to a higher energy state

Answer 32

* 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

Question 33

How does an excited state electron move back down to a lower energy level and what happens when it does?

Answer 33

Excited state electron **can move back down** to a lower energy level **if it releases the energy difference as electromagnetic radiation**

Question 34

Explain how movement of an excited state electron back down to a lower energy level can be used to identify hydrogen in the atmosphere

Answer 34

If an **excited state electron** in hydrogen drops from **n = 3** to **n = 2**, it releases electromagnetic radiation of wavelength **656.3 nm**

Question 35

Explain the difference between the absorption and the emission spectrum of hydrogen

Question 36

Explain the relationship between photon energy level and absorption by hydrogen

Question 37

What is the formula to calculate the energy of a photon?

Answer 37

E = hc/λ

Question 38

If an electron absorbed 9.5eV of energy, what wavelength does this correspond to on the electromagnetic spectrum?

Answer 38

* 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**

Question 39

What range of wavelengths on the electromagnetic energy spectrum are radiated from the Sun?

Answer 39

10^2 - 10^5

Question 40

What range of wavelengths on the electromagnetic energy spectrum are radiated from the human body?

Answer 40

10^4

Question 41

What type of spectroscopy would detect the range of wavelengths radiated from the human body?

Answer 41

IR