Wave speed formula relates frequency, speed, and wavelength Steps:

• Convert wavelength to meters: 15 cm = 0.15 m.
• Recall formula for electromagnetic waves: frequency f = speed of light c / wavelength λ.
• Substitute values: f = (3.0 × 10^8 m/s) / 0.15 m.
• Compute: 3.0 × 10^8 / 0.15 = 2.0 × 10^9 Hz. Why A is correct:
• Matches exact result from f = c / λ, the fundamental relation for wave frequency. Why the others are wrong:
• B: Overestimates by factor of 2.25, possibly from dividing by 0.066 m instead.
• C: Overestimates by factor of 10, likely from treating 15 cm as 1.5 cm (0.015 m).
• D: Overestimates by factor of 2.5, perhaps from approximate division like 3 / 0.12.

Final answer: A