(a) A red laser pointer emits light with a wavelength of \(650 \mathrm{nm}\). What is the frequency of this light? (b) What is the energy of one of these photons? (c) The laser pointer emits light because electrons in the material are excited (by a battery) from their ground state to an upper excited state. When the electrons return to the ground state, they lose the excess energy in the form of \(650 \mathrm{nm}\) photons. What is the energy gap between the ground state and excited state in the laser material?

Short Answer

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\(a)\) The frequency of the red laser light is approximately \(4.62 \times 10^{14} \ Hz\). \(b)\) The energy of one photon of the red laser light is approximately \(3.06 \times 10^{-19} \ J\). \(c)\) The energy gap between the ground state and the excited state in the laser material is approximately \(3.06 \times 10^{-19} \ J\).

Step by step solution

01

Write the given wavelength in meters.

The given wavelength is 650 nm, which is equivalent to \(6.50 \times 10^{-7} \ m\) in meters.
02

Use the speed of light formula to find the frequency.

We can find the frequency using the formula, \(c = \lambda \nu\). Since the speed of light (c) is approximately \(3.0 \times 10^8 \ m/s\), we get: \(\nu = \frac{c}{\lambda} = \frac{3.0 \times 10^8 \ m/s}{6.50 \times 10^{-7} \ m} = 4.62 \times 10^{14} \ Hz\) The frequency of the red laser light is approximately \(4.62 \times 10^{14} \ Hz\). #b. Calculating the energy of one photon#
03

Use Planck's constant to find the energy of a single photon.

The energy of a photon can be found using the formula, \(E = h \nu\). Planck's constant (h) is approximately \(6.63 \times 10^{-34} \ Js\). By substituting the values, we get: \(E = (6.63 \times 10^{-34} \ Js)(4.62 \times 10^{14} \ Hz) = 3.06 \times 10^{-19} \ J\) The energy of one photon of the red laser light is approximately \(3.06 \times 10^{-19} \ J\). #c. Finding the energy gap between the ground state and excited state#
04

Analyze the energy conservation.

The energy gap between the ground state and excited state is equal to the energy of a single photon. Thus, the energy gap is also \(3.06 \times 10^{-19} \ J\). The energy gap between the ground state and the excited state in the laser material is approximately \(3.06 \times 10^{-19} \ J\).

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