Diffraction, interference, single and double slit setups

[Yangi]

Homework Statement

Hey,
due to the corona—virus here in Germany all schools are closed down. Today our teacher gave us two tasks but I'm not sure which formulars I should use.

1.Calculate the Angel below the 3rd.diffraction minimum behind a single slith that's 0.3 mm width. The laserpointer is a red one with a wave length of 630nm.

2.A parallel red light falls through a double slit. Interference appears on a screen that's 3meters away from the lightsource.The distance between the 1st and zero maximum is 4mm. The column spacing d=0,5mm.
Calculate the Wave length of the red light

Thanks in advance

Relevant Equations

I have added a picture with my attempts to find a solution and equations..

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[etotheipi]

I think you might have forgotten to multiply by 3 on your calculator for the first part. Also make sure to write $\theta$ in the argument of the $\sin$ function in your working! Also note that for small $\theta$, we have $\sin{\theta} \approx \theta$ so often we can just use $\theta = \frac{\lambda}{s}$ - though in this case it's small enough that the two are the same to pretty high precision!

I agree with your part 2.

 

[Yangi]

Thank your for the fast reply. I corrected the first one now I got 0.30 degree is this right ?

 

[etotheipi]

Thank your for the fast reply. I corrected the first one now I got 0.30 degree is this right ?

If you do want to convert it to degrees, I get a value of 0.36 degrees.