Worksheet: Energy and Wavelength

In this worksheet, we will practice using the Planck constant and speed of light to convert between energies and wavelengths of electromagnetic waves.

Q1:

Atomic emission spectra of the hydrogen atom show a red line at a wavelength of 656 nm. Given that the speed of light is 3.00×10/ms and Planck’s constant is 6.626×10Js, what is the energy possessed by one photon at this wavelength?

  • A1.010×10J
  • B3.300×10J
  • C4.573×10J
  • D3.030×10J

Q2:

The atomic emission spectrum of the hydrogen atom shows a violet line at a wavelength of 434.0 nm. Calculate the energy of one photon at this wavelength. Use a value of 2.998×10/ms for the speed of light and 6.626×10Js for Planck’s constant.

  • A2.180×10J
  • B4.577×10J
  • C6.912×10J
  • D1.526×10J

Q3:

Heated thallium ions emit photons with an energy of 8.644×10 J.

Calculate the wavelength of the emitted photons.

Calculate the energy per mole of emitted photons.

Q4:

Heated barium ions emit photons with an energy of 2.722 eV.

Calculate the wavelength of the emitted photons.

Calculate the energy per mole of emitted photons.

Q5:

In a flame test, bismuth atoms emit photons with an energy of 4.042 eV.

Calculate the wavelength of the emitted photons.

Calculate the energy per mole of the emitted photons.

Q6:

Mercury atoms in a high-pressure lamp emit photons with an energy of 6.705 eV.

Calculate the wavelength of the emitted photons.

Calculate the energy per mole of emitted photons.

Q7:

The atomic emission spectrum of nitrogen contains a strong line corresponding to photons with an energy of 1.656×10 J.

Calculate the wavelength of the emitted photons. Give your answer to 1 decimal place.

Calculate the energy per mole of emitted photons.

Q8:

How many infrared photons with a wavelength of 1.30×10 m must be absorbed by 190 g of water to increase the temperature from 25.0 to 35.0C? The specific heat capacity of water is 4.184 J/g⋅K.

Q9:

Chlorophyll a strongly absorbs light with a wavelength of 680 nm. What is the energy of a photon of this light?

  • A3.92×10 J
  • B9.58×10 J
  • C2.92×10 J
  • D6.77×10 J
  • E5.15×10 J

Q10:

Heated sodium ions emit photons with an energy of 3.373×10 J.

Calculate the wavelength of the emitted photons.

Calculate the energy per mole of emitted photons.

Q11:

A laser emits photons with an energy of 3.027×10 J.

Calculate the frequency of the emitted photons.

  • A4.850×10 Hz
  • B4.568×10 Hz
  • C5.256×10 Hz
  • D5.181×10 Hz
  • E4.001×10 Hz

Calculate the energy per mole of emitted photons.

Q12:

The emission spectrum of mercury vapor contains a bright green line at 546.1 nm. How much energy must an electron in a mercury atom release to produce a photon at this wavelength?

  • A1.21×10 J
  • B1.08×10 J
  • C8.29×10 J
  • D3.64×10 J
  • E3.01×10 J

Q13:

The eye of a reptile sends a visual signal to its brain when the visual receptors are struck by photons with a wavelength of 865 nm. The signal is sent only if the total energy of the photons is greater than 3.30×10 J. Calculate the minimum number of photons that must strike the eye in order to trigger a signal.

  • A2.06×10
  • B1.14×10
  • C1.03×10
  • D1.44×10
  • E2.30×10

Q14:

A medical radiographic device emits an X-ray photon with a wavelength of 2.090×10 m. Calculate the energy of this photon.

Q15:

A neon sign emits photons with a wavelength of 640 nm. Calculate the energy of one emitted photon.

  • A4.24×10 J
  • B4.68×10 J
  • C4.94×10 J
  • D1.94×10 J
  • E3.10×10 J

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