Two slits are separated by 0.320 mm. A beam of 500 nm light strikes the slits, producing an interference pattern. Determine the number of maxima observed in the angular range `- 30.0^(@) lt theta lt 30.0^(@)`.

Explanation

At `30.0^(@), d sin theta = m lambda`
`(3.20 xx 10^(-4) m ) sin 30.0^(@) = m (500 xx 10^(-9) m)`
So, `m = 320`
There are 320 maxima ot the right, 320 to the left, and one for
`m = 0` straight ahead.
Therefore, there are 641 maxima.