Final answer:
The energy of a photon from a red laser, with a wavelength of 690 nm, is approximately 2.88 x 10^-19 Joules, calculated using Planck's constant and the speed of light.
Step-by-step explanation:
The student asked to calculate the energy of a photon emitted by a red laser pointer with a wavelength of 690 nm. To find this, we can use the formula E = h*c/λ, where E is the energy of a photon, h is Planck's constant (6.626 × 10-34 Joule·seconds), c is the speed of light (3 × 108 meters/second), and λ is the wavelength of the light (in meters).
First, convert the wavelength from nanometers to meters: 690 nm = 690 × 10-9 meters. Then apply the formula:
E = (6.626 × 10-34 J·s) * (3 × 108 m/s) / (690 × 10-9 m)
E ≈ 2.88 × 10-19 Joules per photon (rounded to three significant figures).
The energy of a photon can be calculated using the formula:
E = hc/λ
where:
E = energy of the photon
h = Planck's constant (6.626 × 10-34 J·s)
c = speed of light (3.00 × 108 m/s)
λ = wavelength of the light
Substituting the given values, we have:
E = (6.626 × 10-34 J·s)(3.00 × 108 m/s)/(690 × 10-9 m)
Calculating the numerical value, the energy of a photon of red light with a wavelength of 690 nm is approximately 2.87 × 10-19 J (joules).
The energy of a red light photon with a wavelength of 690 nm is approximately 2.88 × 10-19 Joules.