Q: A photon has a wavelength of $$500\ \text{nm}. $$What is its momentum?

$$p = \frac{h}{\lambda} = \frac{6.626 \times 10$$^{-34}$$\ \text{J}\cdot\text{s}}{500 \times 10$$^{-9}$$\ \text{m}} = 1.33 \times 10$$^{-27}$$\ \text{kg}\cdot\text{m/s}$$

Q: What is the de Broglie wavelength of an electron moving at $$2.0 \times 10^6$\ \text{m/s}$$? (Electron mass $$m_e = 9.11 \times 10$$^{-31}$$\ \text{kg})$$

$$\lambda = \frac{h}{mv} = \frac{6.626 \times 10$$^{-34}$$}{9.11 \times 10$$^{-31}$$ \times 2.0 \times 10^6$} = 3.63 \times 10$$^{-10}$$\ \text{m}$$

Q: Which of the following correctly describes alpha decay?

A nucleus emits a helium nucleus ($$^4_2\text{He}).$$

Question 1

Which of the following best describes Planck's hypothesis regarding black body radiation?

Accepted Answer

Energy is emitted in discrete packets called photons, each with energy $$E = h 
u.$$

Question 2

A photon has a wavelength of $$500\ 	ext{nm}. $$What is its momentum?

Accepted Answer

$$p = \frac{h}{\lambda} = \frac{6.626 	imes 10$$^{-34}$$\ 	ext{J}\cdot	ext{s}}{500 	imes 10$$^{-9}$$\ 	ext{m}} = 1.33 	imes 10$$^{-27}$$\ 	ext{kg}\cdot	ext{m/s}$$

Question 3

Which experiment provided evidence for the wave-particle duality of light?

Accepted Answer

The double slit experiment

Question 4

According to the Bohr model, what is the energy of the electron in the first orbit of hydrogen?

Accepted Answer

$$E_1 = -13.6$$\ 	ext{eV}$$

Question 5

What is the de Broglie wavelength of an electron moving at $$2.0 	imes 10^6$\ 	ext{m/s}$$? (Electron mass $$m_e = 9.11 	imes 10$$^{-31}$$\ 	ext{kg})$$

Accepted Answer

$$\lambda = \frac{h}{mv} = \frac{6.626 	imes 10$$^{-34}$$}{9.11 	imes 10$$^{-31}$$ 	imes 2.0 	imes 10^6$} = 3.63 	imes 10$$^{-10}$$\ 	ext{m}$$

Question 6

Which statement best describes the photoelectric effect?

Accepted Answer

Electrons are emitted from a metal only when the incident light has a frequency above a threshold value.

Question 7

Which equation represents the uncertainty principle?

Accepted Answer

$$\Delta x \Delta p \geq \frac{\hbar}{2}$$

Question 8

In the quantum mechanical model of the atom, what does the wave function $$\psi$$ represent?

Accepted Answer

The probability amplitude for the electron's position.

Question 9

Which principle explains why no two electrons in an atom can have the same set of quantum numbers?

Accepted Answer

Pauli exclusion principle

Question 10

A radioactive isotope has a half-life of $$10\ 	ext{days}. If $$you start with $$80\ 	ext{g}$$, how much remains after $$30\ 	ext{days}$$?

Accepted Answer

$$20\ 	ext{g}$$

Question 11

Which of the following correctly describes alpha decay?

Accepted Answer

A nucleus emits a helium nucleus ($$^4_2	ext{He}).$$

Question 12

What is the binding energy per nucleon for a nucleus with total binding energy $$B = 120\ 	ext{MeV}$$ and $$A = 20$$ nucleons?

Accepted Answer

$$6\ 	ext{MeV}$$

Question 13

Which conservation law is always obeyed in nuclear reactions?

Accepted Answer

Conservation of nucleon number

Question 14

A $$^{14}_{6}	ext{C}$$ nucleus undergoes beta decay. What is the resulting nucleus?

Accepted Answer

$$^{14}_{7}	ext{N}$$

Question 15

The Q-value of a nuclear reaction is defined as:

Accepted Answer

The difference in mass-energy between reactants and products.

Question 16

In the double slit experiment with electrons, what is observed on the screen?

Accepted Answer

An interference pattern similar to light.

Question 17

Which of the following is NOT a consequence of the uncertainty principle?

Accepted Answer

The energy of a photon is quantized.

Question 18

Which atomic model first explained the discrete spectral lines of hydrogen?

Accepted Answer

Bohr model

Question 19

A gamma decay process results in:

Accepted Answer

Emission of a high-energy photon with no change in nucleon number.

Question 20

Which force is responsible for holding protons and neutrons together in the nucleus?

Accepted Answer

Strong nuclear force

Modern Physics: Quantum Theory, Atomic Structure, and Nuclear Physics

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