Q: What is the energy of a single photon with a wavelength of $$525 \text{ nm}$$? (Use $$h = 6.626 \times 10$$^{-34}$$ \text{ J} \cdot \text{s}$$ and $$c = 3.00 \times 10^8$ \text{ m/s})$$

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 \times 10$$^{-34}$$ \times 3.00 \times 10^8$}{525 \times 10$$^{-9}$$} = 3.79 \times 10$$^{-19}$$ \text{ J}$$

Q: A 1-watt light bulb emits all its energy at a wavelength of $$525 \text{ nm}. $$How many photons are emitted per second? ($$h = 6.626 \times 10$$^{-34}$$ \text{ J} \cdot \text{s}$$, $$c = 3.00 \times 10^8$ \text{ m/s})$$

$$\text{Number of photons} = \dfrac{1 \text{ J/s}}{3.79 \times 10$$^{-19}$$ \text{ J}} = 2.64 \times 10$$^{18}$$

Q: If the energy required to dislodge electrons from sodium metal is $$275 \text{ kJ/mol}$$, what is the minimum wavelength of light (in nm) that can cause the photoelectric effect? ($$h = 6.626 \times 10$$^{-34}$$ \text{ J} \cdot \text{s}$$, $$c = 3.00 \times 10^8$ \text{ m/s}$$, $$N_A = 6.022 \times 10$$^{23}$$ \text{ mol}^{-1})$$

$$\lambda = \dfrac{hcN_A}{275 \times 10^3$} = 434 \text{ nm}$$

Question 1

Which of the following types of electromagnetic radiation has the shortest wavelength?

Accepted Answer

Gamma rays

Question 2

Arrange the following types of electromagnetic radiation in order of increasing energy per photon: visible light, X-rays, infrared.

Accepted Answer

Infrared \u003c visible light \u003c X-rays

Question 3

Which property of electromagnetic waves allows them to bend around obstacles and create patterns when passing through slits?

Accepted Answer

Diffraction

Question 4

What is the energy of a single photon with a wavelength of $$525 	ext{ nm}$$? (Use $$h = 6.626 	imes 10$$^{-34}$$ 	ext{ J} \cdot 	ext{s}$$ and $$c = 3.00 	imes 10^8$ 	ext{ m/s})$$

Accepted Answer

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 	imes 10$$^{-34}$$ 	imes 3.00 	imes 10^8$}{525 	imes 10$$^{-9}$$} = 3.79 	imes 10$$^{-19}$$ 	ext{ J}$$

Question 5

A 1-watt light bulb emits all its energy at a wavelength of $$525 	ext{ nm}. $$How many photons are emitted per second? ($$h = 6.626 	imes 10$$^{-34}$$ 	ext{ J} \cdot 	ext{s}$$, $$c = 3.00 	imes 10^8$ 	ext{ m/s})$$

Accepted Answer

$$	ext{Number of photons} = \dfrac{1 	ext{ J/s}}{3.79 	imes 10$$^{-19}$$ 	ext{ J}} = 2.64 	imes 10$$^{18}$$

Question 6

Which of the following best describes constructive interference?

Accepted Answer

Waves interact so that they add together to make a larger wave

Question 7

According to Einstein's explanation of the photoelectric effect, what is required for electrons to be emitted from a metal surface?

Accepted Answer

The light must have a minimum frequency (threshold frequency)

Question 8

If the energy required to dislodge electrons from sodium metal is $$275 	ext{ kJ/mol}$$, what is the minimum wavelength of light (in nm) that can cause the photoelectric effect? ($$h = 6.626 	imes 10$$^{-34}$$ 	ext{ J} \cdot 	ext{s}$$, $$c = 3.00 	imes 10^8$ 	ext{ m/s}$$, $$N_A = 6.022 	imes 10$$^{23}$$ 	ext{ mol}^{-1})$$

Accepted Answer

$$\lambda = \dfrac{hcN_A}{275 	imes 10^3$} = 434 	ext{ nm}$$

Question 9

Which observation corresponds to shining 325 nm light on a metal surface in the photoelectric effect experiment?

Accepted Answer

Photoelectrons with kinetic energy of 155 kJ/mol are observed

Question 10

Which of the following colors of visible light has the highest energy per photon?

Accepted Answer

Blue

Question 11

What will happen if a metal surface is struck with violet light, compared to yellow light, in the context of the photoelectric effect?

Accepted Answer

Electrons will be ejected, and they will have greater kinetic energy than those ejected by yellow light

Question 12

Which equation correctly relates the energy of a photon to its frequency?

Accepted Answer

$$E = h 
u$$

Question 13

Which of the following statements about the electromagnetic spectrum is TRUE?

Accepted Answer

Gamma rays have the highest energy

Question 14

Which phenomenon is responsible for the pattern observed when light passes through two closely spaced slits?

Accepted Answer

Interference

Question 15

If a photon has more energy than the binding energy of an electron in a metal, what happens to the excess energy?

Accepted Answer

It becomes the kinetic energy of the ejected electron

Question 16

Which of the following is NOT a property of traveling particles, as compared to waves?

Accepted Answer

Particles can bend around obstacles

Question 17

What is the relationship between frequency ($$
u) $$and wavelength ($$\lambda) $$for electromagnetic waves?

Accepted Answer

$$c = \lambda 
u$$

Question 18

Which of the following best describes destructive interference?

Accepted Answer

Waves interact so that they cancel each other out

Question 19

Which type of electromagnetic radiation is most likely to cause ionization of biological molecules?

Accepted Answer

Ultraviolet

Electromagnetic Spectrum and Wave Properties: Interference, Diffraction, and the Photoelectric Effect

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