Q: A 100-watt light bulb emits light at a wavelength of $$525 nm. $$How many photons are emitted per second? ($$h = 6.626 \times 10$$^{-34}$$ J·s, c = 3.00$$ \times $$10^8 m/s)$$

$$2.64 \times 10$$^{20}$$ photons/s

Q: A nitrogen gas laser emits a pulse of light with a wavelength of $$337 nm $$and a total energy of $$3.83 mJ. $$How many photons are in the pulse? ($$h = 6.626 \times 10$$^{-34}$$ J·s, c = 3.00$$ \times $$10^8 m/s)$$

$$6.49 \times 10$$^{15}$$ photons

Question 1

Which of the following statements best explains why the photoelectric effect provided evidence for the particle nature of light?

Accepted Answer

Electrons are ejected from a metal surface only when the frequency of the light exceeds a threshold value, regardless of intensity.

Question 2

A light source emits radiation with a wavelength of $$4.50 	imes 10$$^{-7}$$ m. What is the frequency of this radiation? (Speed of light c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$6.67 	imes 10$$^{14}$$ Hz

Question 3

Which of the following best describes the difference between a continuous spectrum and a line spectrum?

Accepted Answer

A continuous spectrum contains all wavelengths within a given range, while a line spectrum contains only specific wavelengths characteristic of an element.

Question 4

Calculate the energy of a single photon of green light with a wavelength of $$525 nm$$. ($$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$3.79 	imes 10$$^{-19}$$ J

Question 5

Which experiment provided evidence for the wave nature of light by demonstrating constructive and destructive interference?

Accepted Answer

The double-slit experiment

Question 6

According to Planck's quantum theory, which of the following statements is correct?

Accepted Answer

Energy is emitted or absorbed only in discrete packets called quanta.

Question 7

A 100-watt light bulb emits light at a wavelength of $$525 nm. $$How many photons are emitted per second? ($$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$2.64 	imes 10$$^{20}$$ photons/s

Question 8

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

Accepted Answer

$$E = hc / \lambda$$

Question 9

The Rydberg equation for the hydrogen atom is $$\frac{1}{\lambda} = R_H \left[ \frac{1}{n_1$^2} - \frac{1}{n_2$^2} \right]. $$What does $$n_2$$ represent in this equation?

Accepted Answer

The principal quantum number of the higher energy level

Question 10

Which of the following best explains why each element has a unique emission spectrum?

Accepted Answer

Each element has electrons that can occupy only specific, quantized energy levels.

Question 11

An electron in a hydrogen atom transitions from $$n=4 to$$ $$n=2. $$Using the Bohr model, which of the following statements is true?

Accepted Answer

The atom emits a photon with energy equal to the difference between the two energy levels.

Question 12

Which of the following is a correct statement about the speed of electromagnetic waves in a vacuum?

Accepted Answer

All electromagnetic waves travel at the same speed, $$c = 3.00 	imes 10^8$ m/s, in a vacuum.

Question 13

A nitrogen gas laser emits a pulse of light with a wavelength of $$337 nm $$and a total energy of $$3.83 mJ. $$How many photons are in the pulse? ($$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$6.49 	imes 10$$^{15}$$ photons

Question 14

Which of the following is NOT a property of electromagnetic waves?

Accepted Answer

Their speed in a vacuum depends on their frequency.

Question 15

Which of the following best describes the ground state of the hydrogen atom according to the Bohr model?

Accepted Answer

The electron is at $$n=1$$, closest to the nucleus, with the lowest possible energy.

Question 16

If the energy of a photon is $$3.39 	imes 10$$^{-19}$$ J, what is its wavelength in nanometers? (h = 6.63$$ 	imes $$10^{-34} J$$·s, $$c = 3.00 	imes 10^8$ m/s)

Accepted Answer

$$587 nm$$

Question 17

Which of the following is a real-world application of emission spectra?

Accepted Answer

Identifying unknown elements in distant stars using their spectral lines.

Question 18

Which of the following is a quantized property in atomic structure?

Accepted Answer

The energy levels that electrons can occupy.

Question 19

Which of the following equations can be used to calculate the energy difference when an electron transitions between two energy levels in the hydrogen atom?

Accepted Answer

$$\Delta E = -2.18 	imes 10$$^{-18}$$ J \left( \frac{1}{n_f^2$} - \frac{1}{n_i^2$} ight)$$

chapter 6 lec 1

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