# Physics

posted by .

Light from a sodium lamp ( wavelength= 589 nm) illuminates a narrow slit and is observed on a screen 75 cm behind the slit. The dstance between the first and third dark fringes is 7.5 mm. What is the width (in mm) of the slit?

Cant seem to get the answer =/

• Physics -

Read the "single slit diffraction" section of
http://en.wikipedia.org/wiki/Diffraction
The formula you need can be found there.

The angle theta at any distance x from the central maximum is
theta = tan^-1 (x/75)
where x is in cm

• Physics -

I've tried that and im still not getting the answer (which is 0.12 mm) =/ i used that formula to give me the theta and i substituted that into the d= lambda/ sin theta

## Similar Questions

1. ### Physics

A laser emitting at 632.8nm illuminates a double slit. A screen is positioned 2.00 m from the slits. Interference fringes are observed with a separation of 1.0 cm. (a) Determine the separation of the slits. (b) Determine the angle …
2. ### Physics

In an experiment using sodium light (λ=589 nm), the slits are 1.2 μm wide. You notice that every fourth fringes missing. a) What is the slit separation?
3. ### PHYSIC-als-------------->>

A helium-neon laser ( λ=633nm) illuminates a single slit and is observed on a screen 1.50m behind the slit. The distance between the first and second minima in the diffraction pattern is 4.75 mm. What is the width (in mm) of the …
4. ### physices

mean: a double-slit interference experiment is set up in a laboratory using a source of blue monochromatic light of wavelength 475 nm.the separation of two slit is 0.40mm and the distance from the slit to the screen where the fringes …
5. ### Physics 2

Light with λ = 530 nm passes through a single slit and then illuminates a screen 9.0 m away. If the distance on the screen from the first dark fringe to the center of the interference pattern is 3.20 mm, what is the width of the …
6. ### Physics

Light of a red laser (wavelength λ=650 nm) goes through a narrow slit which is only a=2 microns wide. After the light emerges from the slit, it is visible on a screen that is L=5 meters away from the slit. What is the approximate …
7. ### physics

a screen is placed at a distance of 1.5 m from a narrow slit. the slit is illuminated by light of wavelength 6000 angstrom if the first minimum on either side of the central maximum is at a distance of 5 mm from , find the width of …
8. ### Physics

Light of wavelength 550 nm strikes a single slit of width 1.00 x 10-5 m that is 100.0 cm away from a screen. The screen is 36 cm wide, with the central maximum falling exactly at its centre. How many dark fringes in total will be seen …
9. ### physics

A monochromatic light of wavelength 587.5nm illuminates a slit of width 0.75mm. At what distance from the slit should a screen be placed so that the first dark fringe is at 0.85mm from the center of the diffraction pattern?
10. ### physics

A screen is placed 50cm away from a slit lit by a monochromatic light of wavelength 690nm. The distance seperating the first dark fringe and the third dark fringe in the diffraction pattern is 3mm. Calculate the width of the slit.

More Similar Questions