Experiment to measure the wavelength of Monochromatic

Draw a diagram of this experiment

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Step 1

Focus the telescope on a distant object

Step 2

Adjust the crosshairs so that they’re in focus at the same time

Step 3

Set up apparatus as shown and adjust the slit so that the clearest rectangle of light is seen

Step 4

Place the diffraction grating on the table at a right angle to the collimator

Step 5

Level the table

Step 6

Looking through the telescope, rotate it to the right until the crosshairs are in the centre of the first green line and record the angle (θ_R)

Step 7

Return the telescope to the straight through position

Step 8

Looking through the telescope, rotate it to the left until the crosshairs are in the centre of the first green line and record the angle (θ_L)

Step 9

Calculate θ from θ= (θ_R - θ_L)/2

Step 10

Calculate λ from Nλ= dSinθ

Conclusion

We found the wave length of green light