Q: A wave has a wavelength of $2.0\ \mathrm{m}$ and a frequency of $1.5 \times 10^8\ \mathrm{Hz}$. What is the speed of the wave?

$3.0 \times 10^8\ \mathrm{m/s}$

Q: A 2.5 g Ping-Pong ball travels at $15.6\ \mathrm{m/s}$. What is its de Broglie wavelength?

$1.7 \times 10^{-32}\ \mathrm{m}$

Question 1

Which of the following statements best describes the nature of electromagnetic radiation?

Accepted Answer

It is a form of radiant energy that has both electric and magnetic wave components.

Question 2

A wave has a wavelength of $2.0\ \mathrm{m}$ and a frequency of $1.5 	imes 10^8\ \mathrm{Hz}$. What is the speed of the wave?

Accepted Answer

$3.0 	imes 10^8\ \mathrm{m/s}$

Question 3

Which equation correctly relates the speed of light $(c)$, wavelength $(\lambda)$, and frequency $(
u)$?

Accepted Answer

$c = \lambda 
u$

Question 4

Planck’s solution to the blackbody radiation problem introduced which concept?

Accepted Answer

Energy is emitted or absorbed in discrete units called quanta.

Question 5

The energy of a photon is given by $E = h 
u$. If the frequency of a photon is doubled, what happens to its energy?

Accepted Answer

The energy is doubled.

Question 6

Which phenomenon provided evidence for the particle nature of light?

Accepted Answer

Photoelectric effect

Question 7

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?

Accepted Answer

The principal quantum number of the higher energy level

Question 8

According to the Bohr model, what is the energy of an electron in the $n$th orbit of hydrogen?

Accepted Answer

$E_n = -hcR_H \frac{1}{n^2}$

Question 9

A hydrogen atom transitions from $n=3$ to $n=1$. What is the correct formula to calculate the wavelength of the emitted photon?

Accepted Answer

$\lambda = \frac{hc}{\Delta E}$

Question 10

Louis de Broglie proposed that matter has wave-like properties. What is the de Broglie wavelength of a particle?

Accepted Answer

$\lambda = \frac{h}{mv}$

Question 11

A 2.5 g Ping-Pong ball travels at $15.6\ \mathrm{m/s}$. What is its de Broglie wavelength?

Accepted Answer

$1.7 	imes 10^{-32}\ \mathrm{m}$

Question 12

Heisenberg’s uncertainty principle can be mathematically expressed as:

Accepted Answer

$\Delta x \Delta m v \geq \frac{h}{4\pi}$

Question 13

Which of the following best explains why the de Broglie wavelength of a macroscopic object, such as a golf ball, is not observable?

Accepted Answer

Its mass is so large that the wavelength is extremely small.

Question 14

If the uncertainty in the position $(\Delta x)$ of an electron is $1\%$ of the radius of a hydrogen atom $(5 	imes 10^{-11}\ \mathrm{m})$, what is the minimum uncertainty in its velocity $(\Delta v)$? (Electron mass $= 9.11 	imes 10^{-31}\ \mathrm{kg}$)

Accepted Answer

$5 	imes 10^4\ \mathrm{m/s}$

Question 15

Which of the following is NOT a consequence of Heisenberg’s uncertainty principle?

Accepted Answer

The energy of a photon can be measured with absolute precision.

Electronic Structure of Atoms: Light, Quantization, and Atomic Models

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