Question

Question #4e709

Answer 1

9 maxima measured from the normal

Explanation:

The equation for determining the orders of maxima seen is:

`nlamda=dsintheta`

Where

`n`= order of maxima (0,1,2,3..)
`d`= separation of slits in grating=`1/(2times10^5)=5times10^-6m`
`theta` =the angle at which the interference patterns are seen (measured normal to the grating)

`lamda` =wavelength = `625times10^-9m`

The maximum angle(`theta`), that is possible is 90 degrees, and `sin90^0=1`

The largest possible order of maxima is therefore `nlamda=d`

So in this example:

`n*(625times10^-9)=(5times10^-6)`

`n=8`

Including the zero order this would give 9 maxima measured from the normal (in practice, 8 observed either side of the zero order central maxima)