A switch
What are the answers choices
I don't really know the answer but maybe north pole and south pole?
Answer:2.6 h
Explanation:
Given
Total Trip distance=450 miles
Meeting starts after 10.8 hours
safe Fastest speed is 55 mi/h
so if he drives all the to the meeting with max speed then it takes 
and total allowable time is 10.8
Therefore longest time he can spend over dinner is 
Answer:
Explanation:
Let the thickness of the film is t and the refractive index of the material of film is n.
When light travels through a sheet of thickness t, the optical path traveled is nt.
When the path of one of slit is covered by a sheet of thickness t, the optical path becomes
x = ( n - 1) t
As the one fringe is shift, so the optical path changed by one wavelength.
i.e., x = λ
So, λ = ( n - 1) t
