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?

  • A 1 . 0 1 0 × 1 0 J
  • B 3 . 3 0 0 × 1 0 J
  • C 4 . 5 7 3 × 1 0 J
  • D 3 . 0 3 0 × 1 0 J

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.

  • A 2 . 1 8 0 × 1 0 J
  • B 4 . 5 7 7 × 1 0 J
  • C 6 . 9 1 2 × 1 0 J
  • D 1 . 5 2 6 × 1 0 J

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.

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.

  • A83.0 mmol
  • B82.4 mmol
  • C77.7 mmol
  • D86.4 mmol
  • E90.9 mmol

Q9:

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

  • A 3 . 9 2 × 1 0 J
  • B 9 . 5 8 × 1 0 J
  • C 2 . 9 2 × 1 0 J
  • D 6 . 7 7 × 1 0 J
  • E 5 . 1 5 × 1 0 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.

  • A 4 . 8 5 0 × 1 0 Hz
  • B 4 . 5 6 8 × 1 0 Hz
  • C 5 . 2 5 6 × 1 0 Hz
  • D 5 . 1 8 1 × 1 0 Hz
  • E 4 . 0 0 1 × 1 0 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?

  • A 1 . 2 1 × 1 0 J
  • B 1 . 0 8 × 1 0 J
  • C 8 . 2 9 × 1 0 J
  • D 3 . 6 4 × 1 0 J
  • E 3 . 0 1 × 1 0 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.

  • A 2 . 0 6 × 1 0
  • B 1 . 1 4 × 1 0
  • C 1 . 0 3 × 1 0
  • D 1 . 4 4 × 1 0
  • E 2 . 3 0 × 1 0

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.

  • A 4 . 2 4 × 1 0 J
  • B 4 . 6 8 × 1 0 J
  • C 4 . 9 4 × 1 0 J
  • D 1 . 9 4 × 1 0 J
  • E 3 . 1 0 × 1 0 J

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