Unit 6 Waves and Light

Which theory was contradicted by experiments with the photoelectric effect?

• Light spreads out after it passes through a small opening. 

• As soon as light strikes metal, electrons will be ejected. 

• Visible light, regardless of color, will cause the ejection of electrons when striking metal. 

• The kinetic energy of ejected electrons depends on the frequency of light that strikes the metal. 

Heinrich Hertz used properties of which type of wave to support the idea that light is also made of waves?

• infrared

• gamma

• microwave

• radio

What is the energy of a photon with a frequency of 3.6 × 10¹⁵ Hz? Planck’s constant is 6.63 × 10^–34 J•s.

• 1.8 × 10^–49 J

• 2.4 × 10^–19 J

• 1.8 × 10^–18 J

• 2.4 × 10^–18 J

The photoelectric effect occurs when _________ are emitted from metal when the metal is struck by light of certain frequencies.

• electrons

• photons

• neutrons

• protons

Which phenomena support only the particle theory of light? Check all that apply.

• reflection

• traveling in a straight path

• interference

• photoelectric effect

• bending around objects

What is the formula for calculating the energy of a photon?

• E = h – f

• E = h + f

• E = hf

Wilam made a chart to summarize the results of experiments with the photoelectric effect.

Which best describes how to correct Wilam’s error?

• The first result should state that frequencies of light that were lower than the frequency threshold of the metal could not eject electrons.

• The second result should state that as soon as light struck the metal, protons were ejected. 

• The second result should state that just before light struck the metal, electrons were ejected. 

• The third result should state that the kinetic energy of the ejected electrons depends only on the frequency of the photons. 

A photon has a frequency of 2.9 × 10^–16 Hz. Planck’s constant is

6.63 × 10^-34 J•s.

The energy of the photon, to the nearest tenths place, is ___ × 10^–49 J.

Which observation supports the idea that light is made of particles?

• Light is produced by the interaction of magnetic and electric fields. 

• Light spreads out after passing through an opening.

• Light diffracts when it hits a barrier. 

• Light moves in a straight path. 

Which describes a relationship when calculating the energy of a photon?

• The energy of the photon is directly proportional to frequency. 

• The energy of the photon is inversely proportional to frequency. 

• As the energy of the photon increases, Planck’s constant increases. 

• As the energy of the photon increases, Planck’s constant decreases.