Typically the micrometer reading giving the deep (and very shan ) null could be 10 mm. (it would normally be expressed to several significant figures, e.g 10.02 mm.)
Other nulls will be found. In a typical experiment the next two null occured at 14.86 mm (less deep) and 13.7 to 14 mm (quite deep broadly spread over this 0.3 mm- long region). Other nulls may be found, becoming increasingly erratic.
At these results show, selection of the correct null is essential. The micrometer should be screwed fully in to start with, then unscrew carefully until the deepest null is found.
along the guide. There are thus two waves; the original, or"incident" wave, and the "reflected" wave travelling in the opposite direction. There are places where their electric fields will be in phase, and other places where they will tend to cancel each other.
Calculate the distance between the two null positions, which is That is; half the wavelength in the waveguide.