Question

The wavelength of blue light is 480 nm. What is frequency of this light?

• A. $4.8 \times 10^9$ Hz
• B. $2.25 \times 10^{14}$ Hz
• C. $6.25 \times 10^{14}$ Hz
• D. $5.25 \times 10^9$ Hz

Hint:

When performing calculations with $\nu = c / \lambda$, you can bypass traditional division by simplifying numbers mentally first. Recognizing that $3 / 4.8$ is identical to the fractional value $5 / 8$ allows you to quickly write down $0.625$ without setting up a long division table.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
Given wavelength λ = 480 nm of blue light, calculate its frequency ν.

Step 2: Key Formula or Approach:
For electromagnetic radiation, c = λ × ν, so ν = c/λ, where c = 3.0 × 10⁸ m s⁻¹.

Step 3: Detailed Explanation:
Convert λ to meters: 480 nm = 480 × 10⁻⁹ m = 4.8 × 10⁻⁷ m. Substitute: ν = (3.0 × 10⁸)/(4.8 × 10⁻⁷) = (3/4.8) × 10¹⁵ = 0.625 × 10¹⁵ = 6.25 × 10¹⁴ Hz.

Step 4: Final Answer:
Frequency is 6.25 × 10¹⁴ Hz, option (C).