WAEC Physics 2021 Paper

Concept:Amplitude is the maximum displacement from the mean position. Wavelength is the distance between two consecutive identical points on the wave.Explanation:The graph shows that the maximum displacement from the equilibrium position is $8\text{ cm}$.Hence, the amplitude is $A = 8\text{ cm}$.The wave completes 3 full cycles over a total distance of $27\text{ cm}$.So, the wavelength is $\lambda = \frac{27\text{ cm}}{3} = 9\text{ cm}$.The given period of $0.125\text{ s}$ is not needed for measuring amplitude or wavelength from this displacement-distance graph.Therefore, the amplitude is $8\text{ cm}$ and the wavelength is $9\text{ cm}$.Answer:Option B: $8\text{ cm}$; $9\text{ cm}$.