Angle problem (easy but I don't find the matter)

In summary, the conversation discusses the famous electron diffraction experiment, where electrons are accelerated by an anode and interact with a graphite target to create an interference pattern. The Bragg condition, which is used to calculate the angle of constructive interference, is given by 2*d*sin(w)=n*lambda. However, for the first maxima, the Bragg condition simplifies to 2*d*sin(w)=lambda. There is confusion about why the angle of the first maxima is labeled as "2w." To understand this, one must draw the direction of the crystal plane producing the Bragg reflection and keep in mind that the angle "w" in Bragg's Law is the glancing angle, not the angle from the normal
  • #1
Kruger
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Consider the famous experiment of electron diffraction. electrons are accelerated by an anode. After this anode there is a graphit target (to create an interference pattern). In this case one has to take the Bragg condition to calculate the angle constructive interference actes. The Bragg condition is given by:

2*d*sin(w)=n*lambda

For the first maxima we get:

2*d*sin(w)=lambda

Now my problem is the following. Look at the picture (shows electron diffraction). The angle the electrons leave the graphit is 2w. Thus, 2w is "the angle of the first maxima".

But why the hell is this angle 2w. I don't get this. I don't know, arghhh. I could derive the Bragg condition and calculate the probability distribution on the wall (in this experiment). But I cannot derive this angle of 2w.

Would be great if someone could help quickly.
 

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  • #2
You'll understand why that angle is labeled as "2w" if you do the following:

1. Draw the direction of the crystal plane that is producing that specific Bragg reflection. (Hint : the crystal plane is not parallel to the surface of the graphite film)

2. Keep in mind that the angle "w" in Bragg's Law is the glancing angle; not the angle from the normal.
 

1. What is an angle problem?

An angle problem is a type of mathematical problem that involves finding the measure of an angle or solving for an unknown angle in a given shape or scenario.

2. How do I solve an angle problem?

To solve an angle problem, you can use various methods such as using the properties of angles (e.g. complementary, supplementary, vertical angles) or using trigonometric functions (e.g. sine, cosine, tangent).

3. Can you provide an example of an angle problem?

Sure, here's an example: Find the measure of angle A in the given triangle if angle B measures 60 degrees and angle C measures 40 degrees. To solve this, we can use the fact that the sum of the angles in a triangle is 180 degrees. So, angle A = 180 - 60 - 40 = 80 degrees.

4. What if I have multiple angle problems in one shape?

If you have multiple angle problems in one shape, you can use the same methods to solve each problem individually. It may also be helpful to label the angles and use the information from one problem to help solve another.

5. Are there any tips for solving angle problems more efficiently?

Yes, here are a few tips: 1) Draw a diagram to visualize the problem, 2) Use the given information to label the angles and identify any relationships between them, 3) If applicable, use the properties of similar or congruent shapes to solve the problem, and 4) Check your answer to ensure it makes sense in the given context.

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