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# The wavelength of the red part of visible light is 760nm. what is its energy​

• Réponse publiée par: jemuelpogi

Problem:

the wavelength of the red part of visible light is 760nm. What is its energy​?

In order to solve for energy, we will first find its frequency. All electromagnetic wave will travel in a vacuum at a speed of                              3 × 10⁸ m/s.

Solving for frequency:

Given:

speed = 3 × 10⁸ m/s

wavelength =  760 nm which is equivalent to 0.00000076 meter

760 nm × 1 m/1,000,000,000 = 0.00000076 m

frequency = ? unknown

Solution:

To solve for frequency you will used the formula                                                   frequency = speed/wavelength (f=cλ)

f = 3 × 10⁸ m/s ÷ 0.00000076 m

= 3 × 10⁸ m/s ÷ 7.6 × 10-⁷ m

=      0.3947 × 10 ¹⁵  /s

=       3.947  × 10¹⁴ Hz

Frequency is equal to 3.947  × 10¹⁴ Hz

Solving for energy

Given:

frequency = 3.947  × 10¹⁴ Hz

h = 6.63 x 10-³⁴ Joules

Energy = unknown

solution:

We can use the formula E=hf

E=hf

= 6.63 x 10-³⁴ Joules/s  × 3.947  × 10¹⁴ /s

=  26.169 x 10 -²⁰  Joules

= 2.6169   x 10 - ¹⁹ Joules

Final

Energy is 2.6169   x 10 - ¹⁹ Joules