It will be 3 wavelengths because 1 cycle = 1 wavelength.
This assumes that the wave has velocity c (is light).
Answer:
Option B
Explanation:
Looking at the 3 galvanometer readings given above, for galvanometer A, the reading is -2 mA.
For galvanometer B, the reading is 4 mA.
While for galvanometer C, the reading is -5 MA
Thus, option B is correct.
B. they both involve wave interaction.