JAMB Physics 2023 Paper

Concept: The wave number depends on the wavelength, which is obtained from the wave speed and frequency. Amplitude is not required for this calculation.Explanation:Given: $A = 0.80\ \mathrm{m}$, $f = 16\ \mathrm{Hz}$, and $v = 20\ \mathrm{m\,s^{-1}}$.Use the wave equation $v = f\lambda$ to find the wavelength:$$\lambda = \frac{v}{f} = \frac{20}{16} = 1.25\ \mathrm{m}.$$The wave number is given by $k = \frac{2\pi}{\lambda}$.With $\pi \approx 3.142$, substitute the value of $\lambda$:$$k = \frac{2 \times 3.142}{1.25} = \frac{6.284}{1.25} = 5.03.$$To one significant figure, $k \approx 5$.Amplitude does not affect the wave number, so it is not needed here.Answer: C. 5