If velocity in a medium is constant, increasing frequency will cause the wavelength to

• A. Wavelength increases
• B. Wavelength remains the same
• C. Wavelength decreases
• D. Wavelength becomes infinite

Answer: (C)

Wavelength is inversely related to frequency when the propagation speed in the medium is fixed. The relationship is λ = v / f, so if the speed v stays the same and you raise the frequency f, the wavelength λ gets shorter. This happens because the wave crests are packed more tightly as frequency increases, so the distance between successive crests shrinks. For a concrete example, if the speed is constant at a certain value, doubling the frequency halves the wavelength. The other possibilities don’t fit because keeping speed fixed means a higher frequency cannot yield a longer or infinite wavelength; it simply reduces the spacing between wavefronts.