A residue from a gunshot is most likely gun powder, which tells you what kind of bullet was shot and the type of gun that was used to shoot the target/victim/person. Some complications may be that there is more than one gun or weapon which uses that residue, so it may be hard to pinpoint it and the bullet can't really tell you who it is unless there's DNA on the bullet, and the chemicals of the bullet may even destroy evidence.
Answer:
Wavelenght is 7,79x10⁻⁵ m
Explanation:
The equation that connects wavelentgh (λ) and frequency (ν) is:
λ=c/ν
Where c is speed of light (3x10⁸ m/sec) and λ is expressed in lenght´s units and ν is expressed in "time⁻¹ " units (for example, sec⁻¹)
According to the details, if we just replace the given value of frequency, we just obtaing wavelenght data:
λ= (3x10⁸ m/sec)/(3,85x10¹² sec⁻¹) = 7,79x10⁻⁵ m