# Homework Help: RE:bright fringes

1. Dec 13, 2008

### noobie!

1. The problem statement, all variables and given/known data
Original Post:
[post]1998976[/post]

2. Relevant equations

3. The attempt at a solution

2. Dec 13, 2008

### heth

Re: bright fringes..

The link to your earlier post isn't working. Did you list relevant equations and show an attempt at a solution when you originally posted this problem?

3. Dec 13, 2008

### noobie!

Re: bright fringes..

hmm,actually i just wanted to know how to figure out the m when i encounter this kind of questions...

eg of a relevant que is:Two slits separated by 0.250 mm produces an interference pattern in which the fifth dark band is located 12.8 cm from the central antinode when the screen is placed a distance of 8.2 meters away.

solution: because central antinode is m=o wright?then counted frm central antinode to 5th dark fringe..so it works out to be 4.5!so frm antinode m=0,go through m=1,2,3,4 when it reaches 4th fringes of bright fringe its m=4.thus que requires 5th dark fringe so the other half contributes which is 4th bright fringes + 1/2 bright fringe ans wll be 4.5,am i wright?if its not the way,could you please show me the exact way to determine m????thank a lot

4. Dec 13, 2008

### heth

Re: bright fringes..

> am i wright.

You certainly are, Wilbur! The dark patches will be halfway between the light patches - so if you imagine/sketch the fringes then count along, you'll get m=4.5 for the 5th dark patch.

5. Dec 13, 2008

### noobie!

Re: bright fringes..

oh,ok,i finally understand..thanks for your kind help,is much appreciated..btw,what's wilbur?haha,thanks a lot yea..what's your name?glad to have you to teach me..thanks..

6. Dec 14, 2008

### heth

Re: bright fringes..

Wilbur and Orville Wright - the Wright brothers.

7. Dec 14, 2008

### Redbelly98

Staff Emeritus
Re: bright fringes..

:rofl: :rofl: :rofl: LOL