Answer:
Part a)

Part b)

Part c)

Explanation:
Part a)
As we know that the speed of light is given as


now the frequency of the light is given as

so we have


Part b)
Position of Nth maximum intensity on the screen is given as

so here we know for 3rd order maximum intensity

n = 3
L = 1.4 m


Part c)
angle of third order maximum is given as



Answer: it will move to the left
Explanation: i remeber doing this
You would have to use the partition force to laaser beam expert on a completely absorbing target
It would do exactly what a rock or a frisbee does when you toss it.
After the engines cut off, it couldn't get any more energy from
anywhere, and after that, as it pushed air aside to get through,
and had air molecules scraping against it, those would slowly
rob kinetic energy from it. Sooner or later it would run out of
kinetic energy, start falling, and it would eventually make either
a big 'SPLOOSH' or else a big 'CRUNCH', depending on exactly
where it returned to Earth's surface.