The ocular lens or eyepiece lens
Answer:
A. Repeat the experiment to be sure the results are valid.
Answer:
λ = 0.905m
Explanation:
TThe wavelength (λ) only depends on the harmonic (n) and the length of the string (L):
λ = 2L/n
λ = 2*1.81m /4
λ = 0.905m