Answer:
a
e(k) = \frac{2a}{c} * sin (\frac{k*a}{2} )
b
G_{v} = \frac{d e(k ) }{dk } = \frac{a^2}{c} * cos (\frac{k* a}{2} )
Explanation:
From the question we are told that
The velocity of transverse waves in a crystal of atomic separation is
Generally the dispersion relation is mathematically represented as
=>
=>
=>
Generally the group velocity is mathematically represented as
Answer:Orient your line of sight directly above the measurement markings.
Explanation: parallax error is a type of systematic error that occurs when an observer views a measurement marking at a wrong angle. This causes a noticeable disparity in results obtained. Therefore the best way to prevent this error is to view and record the data from the correct angle. This can be obtained by:
-Place the measurement device on its edge so it is level with the object being measured.
-Seek out the finest possible edge of the measurement device, or use a device with finer edges.
In conclusion, ask other observers to also take the reading and get an average of their results. It can help cancel out parallax error results.
Answer:
The answer is B
Explanation: Greenhouse gases must be able to change their vibrational state in order to absorb infrared radiation or heat. SO therefore helium is not one of them.
Hope this helps:)
Radio waves have the longest wavelengths