Question

The laser in an audio compact disc uses light of wavelength \( 7.8 \times 10^{-2} \, \text{nm} \). What is the frequency of light emitted by the laser?

• A. \( 1.8 \times 10^{14} \, \text{s}^{-1} \)
• B. \( 2.6 \times 10^{14} \, \text{s}^{-1} \)
• C. \( 5.4 \times 10^{14} \, \text{s}^{-1} \)
• D. \( 3.8 \times 10^{14} \, \text{s}^{-1} \)

Hint:

To calculate frequency, use the formula \( f = \frac{c}{\lambda} \), where \( c \) is the speed of light and \( \lambda \) is the wavelength.

Answer 1

The Correct Option is D

We can use the equation that relates the speed of light (\( c \)), frequency (\( f \)), and wavelength (\( \lambda \)): \[ c = f \lambda \] Where: - \( c = 3 \times 10^8 \, \text{m/s} \) is the speed of light, - \( f \) is the frequency we need to calculate, - \( \lambda = 7.8 \times 10^{-2} \, \text{nm} = 7.8 \times 10^{-10} \, \text{m} \). Rearranging the equation to solve for \( f \): \[ f = \frac{c}{\lambda} \] Substituting the values: \[ f = \frac{3 \times 10^8}{7.8 \times 10^{-10}} = 3.8 \times 10^{14} \, \text{s}^{-1} \] Thus, the correct answer is \( \boxed{3.8 \times 10^{14} \, \text{s}^{-1}} \).