# Calculating frequency of light, wavelength

Calculate the frequency, in units of "per second", of light with a wavelength of (a) 540 nm, and (b) 650 nm.

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#### Solution Preview

For light of known wavelength, you would use the following equation to calculate the frequency:

c=Lv

where

c=speed of light (3.00x10E8m/s), (note: this is a constant; you MAY be asked to memorize it--check with your instructor)

L=wavelength (often written as the greek letter 'lambda' instead of 'L'), and ...

#### Solution Summary

The solution contains a step by step calculation of the frequency of light for part (a) of the problem, including an important exam hint for this type of question. The way this problem is worded, there is one "catch" that students often forget to take into consideration in their solutions to problems of this type.

For part (b) of the problem, the step by step calculation has deliberately been omitted. Instead, the numerical answer is shown, to encourage students to work through the problem on their own, thereby maximizing learning from this problem / solution combination.

Calculating Frequency and Energy

Violet light has a wavelength of about 410 nm. What is its frequency? Calculate the energy of one photon of violet light. What is the energy of 1.0 mol of violet light photons? Compare the energy of photons of violet light with those of red light. Which is more energetic and by what factor?

Frequency of violet light:___________

Energy of one photon:______________

Energy of 1.0 mol of violet photons:_____________

Compare the energy of photons of violet light with those of red light. Which is more energetic and by what factor?

______________________