WAEC Physics 2023 Paper

Concept:For a vibrating wire, the total length of the wire is equal to the number of complete waves on the wire multiplied by the wavelength.Explanation:The diagram shows $2\frac{1}{2}$ complete wave patterns along the wire.So, the number of cycles is $n = 2\frac{1}{2} = \frac{5}{2}$.The length of the wire is $L = 125\ \text{cm} = 1.25\ \text{m}$.Using the relation $L = n\lambda$, we get:$$\lambda = \frac{L}{n} = \frac{1.25}{\frac{5}{2}}$$$$\lambda = 1.25 \times \frac{2}{5} = 0.50\ \text{m}$$The speed of the wave is not needed to find the wavelength.Answer:The wavelength of the wave is $0.50\ \text{m}$, which is Option D.