U5.7 – Photons, Electrons & Spectra

Select the definition of the electron volt.

In the context of electrons in atoms, what is excitation?

Electrons are accelerated through a potential difference of 230 V. Calculate their velocity.

What is meant by the threshold frequency for a metal?

What is the effect on the emission of electrons the frequency of the incident light was increased?

The work functions of four metals are shown above. These metals are irradiated by incident light of 5.2x10¹⁴ Hz, which metals will emit electrons?

If the intensity of incident light was increased on a surface where electrons were already being emitted what would the effect be?

For the first electron to be liberated from a helium atom 24.6 eV of energy is required. Calculate the frequency of light needed.

The work function of an unknown metal is 1.2 eV. Light with energy 3 eV is incident on its surface, calculate the wavelength of the light.

The wavelength of the electrons can be measured by diffraction. An electron gun accelerates electrons into a beam, these were diffracted and upon diffraction the wavelength was found to be 1.23×10^-9m. Calculate the potential difference used to accelerate the electrons from rest into a beam.

Hot gases produce ___________.

Select the correct description of an absorption line spectrum.