Quantum Mechanics - Part 1: Crash Course Physics #43

How did physicists describe light for most of the 19th century?

• As a particle.

• As both a wave and a particle.

• As a wave.

• As a continuous flow of energy.

What is an idealized blackbody designed to do?

• Reflect all incoming light.

• Absorb all incoming light and radiate energy based on its temperature.

• Only radiate heat.

• Emit light at a single frequency.

What was the main problem with the Rayleigh-Jeans Law when predicting blackbody radiation?

• It predicted infinite power at higher frequencies, contradicting energy conservation.

• It predicted that intensity would decrease as frequency increased.

• It only worked for visible light frequencies.

• It couldn't explain why objects radiate heat.

What new concept did Max Planck introduce to resolve the ultraviolet catastrophe?

• Light is purely a wave.

• Energy exists in tiny, discrete packets called quanta.

• Blackbodies do not exist in reality.

• The photoelectric effect.

What happens when light hits a metal plate in the photoelectric effect?

• The plate gets hotter.

• Electrons are released from the plate.

• The light bounces off the plate.

• The plate changes color.

According to the wave theory of light, what would happen if you increased the brightness (intensity) of the light hitting a metal?

• More electrons would be released, and they would move faster.

• Fewer electrons would be released, and they would move slower.

• The electrons would stop being released.

• Only the color of the light would change.

In the particle theory of light, what is the "work function" (W0)?

• The total energy of the light.

• The maximum speed an electron can reach.

• The minimum energy a photon needs to remove an electron from a metal.

• The amount of light reflected by the metal.

When scientists performed experiments on the photoelectric effect, which theory's predictions did the results match?

• The wave theory of light.

• The particle theory of light.

• Neither theory, a new theory was needed.

• Both theories equally.