Answer

Calculating the Frequency of Orange Light (λ = 640 nm)

🔬 Step 1: Use the Wave Equation

The frequency of light can be calculated using the equation:

ν = c / λ

where:
• ν = frequency (in s⁻¹)
• c = speed of light = 3.00 × 10⁸ m/s
• λ = wavelength (in meters)

🧮 Step 2: Convert Wavelength from nm to m

640 nm = 640 × 10⁻⁹ m = 6.40 × 10⁻⁷ m

⚙️ Step 3: Plug Values into the Equation

ν = (3.00 × 10⁸ m/s) / (6.40 × 10⁻⁷ m)
ν = 4.688 × 10¹⁴ s⁻¹

✅ Final Answer

The frequency of orange light with a wavelength of 640 nm is:
ν = 4.688 × 10¹⁴ s⁻¹

❌ Incorrect Options Explained

• 4.688 × 10⁵ s⁻¹ – Too small by a factor of 10⁹
• 1.920 × 10² s⁻¹ – Incorrect; this is far too low for electromagnetic frequencies
• 1.920 × 10¹¹ s⁻¹ – Too small by a factor of 10³
• 2.133 × 10⁻¹⁵ s⁻¹ – Incorrect; inverse logic, likely confused with wavelength scale