Short Answer
21.1 Planck and Quantum Nature of Light

The curve would appear as a Gaussian probability distribution with a large peak in the middle.

The curve would appear as a vertical line.

The curve would appear as a horizontal line.

The curve would appear as a diagonal line correlating intensity to frequency at a 1:1 ratio.
Because there are more gradations to high frequency radiation than low frequency radiation, scientists also thought it possible that a curve titled the ultraviolet catastrophe would occur. Explain what the blackbody radiation curve would look like if this were the case.
 The curve would steadily increase in intensity with increasing frequency.
 The curve would steadily decrease in intensity with increasing frequency.
 The curve would be much steeper than in the blackbody radiation graph.
 The curve would be much flatter than in the blackbody radiation graph.
Energy provided by a light exists in the following quantities: 150 J, 225 J, 300 J. Define one possible quantum of energy and provide an energy state that cannot exist with this quantum.
 65 J; 450 J cannot exist
 70 J; 450 J cannot exist
 75 J; 375 J cannot exist
 75 J; 100 J cannot exist

Planckâ€™s constant is smaller than any previous discovered constant.

Planck hypothesized that energy is quantized rather than continuous.

Planckâ€™s theories meant that classical physics was no longer useful for any system.

Plank discovered the blackbody radiation spectrum.
How many 500mm microwave photons are needed to supply the 8 kJ of energy necessary to heat a cup of water by 10 degrees Celsius?
 8.05 Ã— 10^{28} photons
 8.05 Ã— 10^{26} photons
 2.01 Ã— 10^{26} photons
 2.01 Ã— 10^{28} photons
What is the efficiency of a 100W, 550nm lightbulb if a photometer finds that 1 Ã— 10^{20} photons are emitted each second?
 101 percent
 72 percent
 18 percent
 36 percent

Gamma rays

Radio waves

Ultraviolet light

Xrays

Photons of gamma rays and Xrays carry with them less energy.

Photons of gamma rays and Xrays have longer wavelengths.

Photons of gamma rays and Xrays have lower frequencies.

Photons of gamma rays and Xrays carry with them more energy.
21.2 Einstein and the Photoelectric Effect
According to wave theory, what is necessary to eject electrons from a surface?
 Enough energy to overcome the binding energy of the electrons at the surface
 A frequency that is higher than that of the electrons at the surface
 Energy that is lower than the binding energy of the electrons at the surface
 A very small number of photons
What is the wavelength of EM radiation that ejects 2.00eV electrons from calcium metal, given that the binding energy is 2.71 eV?
 16.1 Ã— 10^{5} m
 6.21 Ã— 10^{âˆ’5} m
 9.94 Ã— 10^{âˆ’26} m
 2.63 Ã— 10^{7} m

6.22 \times 10^{7}\,\text{m}

5.92 \times 10^{5}\,\text{m}

1.24 \times 10^{5}\,\text{m}

5.31 \times 10^{7}\,\text{m}

The lightâ€™s wavelength was about 837 nm.

The lightâ€™s wavelength was about 886 nm.

The lightâ€™s wavelength was about 908 nm.

The lightâ€™s wavelength was about 950 nm.

Solar panels take advantage of the photoelectric effect to store potential energy as heat.

Solar panels take advantage of the photoelectric effect to convert heat energy into power.

Solar panels take advantage of the photoelectric effect to generate power from incoming radiation.

Solar panels take advantage of the photoelectric effect to create light from incoming heat energy.
21.3 The Dual Nature of Light

The photonâ€™s wavelength will drop to zero.

The photonâ€™s wavelength will decrease.

The photonâ€™s wavelength will increase.

The photonâ€™s wavelength will be inverted.

Their momentums are the same because they have the same energy.

The electron has a greater momentum than the photon; photon momentum arises from Planckâ€™s constant which is many orders of magnitude smaller than the mass of an electron.

The photon has a greater momentum than the electron; photon momentum arises from the speed of light which is much faster than an electron can move.

The photon must have a momentum of zero because its rest mass is zero.
A 500nm photon strikes an electron and loses 20 percent of its energy. What is the new momentum of the photon?
 4.24 Ã— 10^{âˆ’27} kg â‹… m/s
 3.18 Ã— 10^{âˆ’27} kg â‹… m/s
 2.12 Ã— 10^{âˆ’27} kg â‹… m/s
 1.06 Ã— 10^{âˆ’27} kg â‹… m/s
A 500nm photon strikes an electron and loses 20 percent of its energy. What is the speed of the recoiling electron?
 7.18 Ã— 10^{5} m/s
 6.18 Ã— 10^{5} m/s
 5.18 Ã— 10^{5} m/s
 4.18 Ã— 10^{5} m/s
When a photon strikes a solar sail, what is the direction of impulse on the photon?
 parallel to the sail
 perpendicular to the sail
 tangential to the sail
 opposite to the sail

Solar sails rely on disorganized strikes from light particles, while sailboats rely on disorganized strikes from air particles.

Solar sails rely on disorganized strikes from air particles, while sailboats rely on disorganized strikes from light particles.

Solar sails rely on organized strikes from air particles, while sailboats rely on organized strikes from light particles.

Solar sails rely on organized strikes from light particles, while sailboats rely on organized strikes from air particles.
The wavelength of a particle is called the de Broglie wavelength, and it can be found with the equation $p=\frac{h}{\mathrm{\xce\xbb}}$ .
Yes or noâ€”Can the wavelength of an electron match that of a proton?
 Yes, a slowmoving electron can achieve the same momentum as a slowmoving proton.
 No, a fastmoving electron cannot achieve the same momentum, and hence the same wavelength, as a proton.
 No, an electron can achieve the same momentum, and hence not the same wavelength, as a proton.
 Yes, a fastmoving electron can achieve the same momentum, and hence have the same wavelength, as a slowmoving proton.

The length of the wave is the same as the diameter of the ball, so they are indistinguishable.

The length of the wave is longer than the diameter of the ball, making the wave difficult to observe.

The length of the wave is much shorter than the diameter of the ball, making the wave difficult to observe.

The ball is not rolling quickly enough to have wavelike qualities.