Answer:
D. all sounds are caused by vibrations
Explanation:
Answer:
tree frog i believe hope its right
Answer:

Explanation:
In this question we have given

we have to find

We know that
optical path difference for bright fringe is given as
Here,
n is order of fringe
and optical path difference for dark fringe is given as
since the light with wavelength
produces its third-order bright fringe at the same place where the light with wavelength
produces its fourth dark fringe
it means
optical path difference for 3rd order bright fringe= optical path difference for forth order dark fringe
Therefore,
...............(1)
Put value of
in equation (1)



He studied galaxies, source: “Hubble proved that many objects previously thought to be clouds of dust and gas and classified as "nebulae" were actually galaxies beyond the Milky”
It darkness or my depression who knows