Question

In a double-slit experiment, two beams of coherent light traveling different paths arrive on a screen some distance away. What is the path difference between the two waves corresponding to the third bright band out from the central bright band?

The path difference between the two waves is three wavelengths.
The path difference between the two waves is two wavelengths.
The path difference between the two waves is four wavelengths.
The path difference between the two waves is one-half of a wavelength.
The path difference between the two waves is one and one-half wavelengths.
The path difference between the two waves is one wavelength.

Answer 1

third bright band

do you think this is construction or destruction?!

Answer 2

i think its constructive?

Answer 3

wait wouldnt it be destructive, bc the two beams of light are traveling in different paths

Answer 4

but.. its a bright band.. right?
if two waves destroyed each other, then it would have been dark correct?

so it must be construction..

Answer 5

ohh that makes sense,then they add up and would the answer be 4 wavelengths?

Answer 6

its third bright band..

so there is central, first. second and third..

central is when you have zero path difference
First bright is when you have 1 wavelength path difference
second bright is when you have 2 wavelength path difference
and therefore
Third bright is when you have 3 wavelength path difference!

Answer 7

so if there were to be a fourth then it would be 4 wavelengths and so on?

Answer 8

correct..

now can you tell me..
for the first DARK fringe.. what should be path difference?

Answer 9

would it be -1 wavelength, I think that is what is shown in the book

Answer 10

-1? :O
lol how can you have -1 wavelength path difference?? how can it be negative..
its like saying "i have -1 mango with me :P"

Answer 11

ahaha never mind, then would it be 0, bc in destructive its not whole numbers its by .5 but in constructive there is only whole numbers

Answer 12

it can't be zero.. zero -> central bright

0.5 --> first dark

1 -- > first bright

1.5---> second dark

2---> second bright

and so on.. get it :D

Answer 13

ohh then how would it be for destructive that is what our professor told us, but i think I understood it wrong

Answer 14

bright - constructive
dark - destructive.. !

Answer 15

ohhh I get it now, oki I have this next question its about destructive I will post and tell you the answer tell me if i am right =) please

Answer 16

ok oki!