Photon Model and Planck's Constant Quiz

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Questions and Answers

What does the photoelectric equation ℎ𝑓𝑓 = 𝜙𝜙 + 𝐾𝐾𝐾𝐾𝑚𝑎𝑎𝑥𝑥 imply about the energy of the incident photon?

It is only considered if the intensity is high.

It is equal to the work function plus the maximum kinetic energy of the emitted electron. (correct)

It is less than the work function of the metal.

It is independent of the work function.

What determines whether electrons will be released from a metal's surface?

The frequency of the incident radiation. (correct)

The temperature of the metal.

The intensity of the incident radiation.

The duration of exposure to light.

Which effect occurs when increasing the intensity of radiation above the threshold frequency?

Decrease in the wavelength of the incident radiation.

Increase in the number of emitted electrons. (correct)

Increase in the kinetic energy of each electron.

Decrease in the work function of the metal.

What is the relationship described by the de Broglie equation?

Wavelength is inversely proportional to momentum. Signup and view all the answers

In the context of the photoelectric effect, what does the threshold frequency represent?

The minimum frequency required to release electrons. Signup and view all the answers

How does increasing the mass of a particle affect its observable wave properties?

The wavelength decreases, making wave properties harder to observe. Signup and view all the answers

If the energy of the incoming photon is exactly equal to the work function, what is the expected outcome?

Electrons are emitted with zero kinetic energy. Signup and view all the answers

What is the implication of wave-particle duality in relation to light?

Light can exhibit both wave-like and particle-like properties depending on the experiment. Signup and view all the answers

What happens to the gold leaf in an electroscope when UV light is shone on the zinc plate?

The gold leaf falls as negative charge is lost. Signup and view all the answers

Why does visible light not cause electrons to be released from the zinc plate?

Electrons require energy above the work function to escape. Signup and view all the answers

What is the work function in the context of the photoelectric effect?

The minimum energy required to free an electron from the surface of a metal. Signup and view all the answers

What is the relationship between the frequency of a photon and its energy?

Energy is directly proportional to frequency. Signup and view all the answers

What is the effect of increasing the intensity of visible light on the photoelectric effect?

It has no effect on electron release. Signup and view all the answers

Which electromagnetic radiation is capable of producing the photoelectric effect on a metal?

Ultraviolet light Signup and view all the answers

What can be concluded from the observation that electrons are released instantaneously when UV light is used?

Photons of UV light have high enough energy to immediately overcome the work function. Signup and view all the answers

How does excess energy from a photon impact a released electron?

It becomes kinetic energy of the electron. Signup and view all the answers

What is the relationship between the energy of a photon and its frequency?

Energy is directly proportional to frequency. Signup and view all the answers

Which of the following is a correct definition of an electronvolt?

The energy transferred when an electron travels through a potential difference of 1 volt. Signup and view all the answers

What is the purpose of using a potential divider in the experiment with LEDs?

To vary the voltage applied across the LED. Signup and view all the answers

How is the value of Planck's constant estimated using LEDs?

By determining the threshold potential difference and the wavelength of the emitted light. Signup and view all the answers

In the experiment setup with LEDs, what does the gradient of the graph of V against 1/λ represent?

The value of Planck's constant multiplied by the speed of light. Signup and view all the answers

Which of the following statements about photons is incorrect?

The energy of a photon is constant regardless of its frequency. Signup and view all the answers

When conducting experiments with different colored LEDs, what is being varied?

The wavelength of emitted light. Signup and view all the answers

What does the term 'threshold p.d.' refer to in the context of LEDs?

The minimum voltage required for the LED to emit light. Signup and view all the answers

Study Notes

The Photon Model

Electromagnetic radiation exhibits wave-like properties such as diffraction and interference.
When interacting with matter, electromagnetic radiation behaves as discrete energy packets called photons.
The energy of a photon is directly proportional to its frequency.
The relationship between energy (E), frequency (f), and wavelength (λ) of a photon is defined by the equation E = hf = hc/λ, where h is Planck's constant (6.63 x 10^-34 Js).
The electronvolt (eV) is a more convenient unit for photon energy than joules, with 1 eV = 1.60 x 10^-19 J.

Determining Planck's Constant using LEDs

LEDs emit light only when the applied voltage exceeds a specific threshold value.
Measuring the threshold voltage and the wavelength of light emitted by different LEDs can be used to estimate the Planck constant.
By plotting a graph of threshold voltage (V) against 1/λ, the gradient is equal to hc/e.
From the gradient, Planck's constant (h) can be calculated.

The Photoelectric Effect

The photoelectric effect occurs when electromagnetic radiation is incident on a metal surface, causing the release of electrons.
Electrons only escape from the metal surface if the incident light has a frequency equal to or greater than the threshold frequency for the specific metal.
Each photon can transfer its energy to a single electron, with any excess energy beyond the work function appearing as the electron's kinetic energy.
The work function (ϕ) is the minimum energy required for an electron to escape the metal surface.
The maximum kinetic energy (KEmax) of the released electron is determined by Einstein's photoelectric equation: hf = ϕ + KEmax.

Wave-Particle Duality

The photoelectric effect suggests a particulate nature of light while diffraction and interference demonstrate its wave-like behavior.
This duality is called wave-particle duality, implying that electromagnetic radiation has both wave and particle characteristics.
De Broglie proposed that all matter exhibits wave-particle duality.
The De Broglie equation relates the wavelength (λ) of a particle to its momentum (p): λ = h/p = h/mv.
This equation highlights that the wavelength of a particle decreases as its mass increases, making wave-like behavior harder to observe for larger particles.

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Description

Explore the concepts of electromagnetic radiation and the photon model in this quiz. You will learn about the wave-like properties of light, the energy of photons, and how to determine Planck's constant using LEDs. Test your knowledge on these fundamental principles of physics!