Thank you for posting your question here at brainly. Below is the solution:
Speed of light is 300,000,000 meters per second or 3E8 m/s
Wavelength = Speed of light divided by the frequency = c / f
3 GHz = 3 GigaHertz = 3E9 Hertz = 3,000,000,000 Hz
L = (300,000,000 m/s) / (3,000,000,000 Hz) = 0.1 meter = 10 centimeters
