Answer:
![\mathbf{\beta = 123.75 \ dB}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cbeta%20%3D%20123.75%20%5C%20dB%7D)
Explanation:
From the question, using the expression:
![125 \ dB = 10 \ log (\dfrac{I}{I_o})](https://tex.z-dn.net/?f=125%20%5C%20dB%20%3D%2010%20%5C%20log%20%28%5Cdfrac%7BI%7D%7BI_o%7D%29)
where;
![I_o = 10^{-12} \ W/m^2](https://tex.z-dn.net/?f=I_o%20%3D%2010%5E%7B-12%7D%20%5C%20W%2Fm%5E2)
![I = 10^{12.5} \times 10^{-12} \ W/m^2](https://tex.z-dn.net/?f=I%20%3D%2010%5E%7B12.5%7D%20%5Ctimes%2010%5E%7B-12%7D%20%5C%20W%2Fm%5E2)
![I = 3.162 \ W/m^2](https://tex.z-dn.net/?f=I%20%3D%203.162%20%5C%20W%2Fm%5E2)
This is a combined intensity of 4 speakers.
Thus, the intensity of 3 speakers = ![\dfrac{3.162\times 3}{4}](https://tex.z-dn.net/?f=%5Cdfrac%7B3.162%5Ctimes%203%7D%7B4%7D)
= 2.372 W/m²
Thus;
![\beta = 10 \ log ( \dfrac{2.372}{10^{-12}} ) \ W/m^2](https://tex.z-dn.net/?f=%5Cbeta%20%3D%2010%20%5C%20%20log%20%28%20%5Cdfrac%7B2.372%7D%7B10%5E%7B-12%7D%7D%20%29%20%5C%20W%2Fm%5E2)
![\mathbf{\beta = 123.75 \ dB}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cbeta%20%3D%20123.75%20%5C%20dB%7D)
At any crime scene, the two greatest challenges to the physical evidence are contamination and loss of continuity.
<h3>What is the meaning of physical evidence?</h3>
In evidence law, physical evidence (also called real evidence or material evidence) is any material object that plays some role in the matter that gave rise to the litigation, introduced as evidence in a judicial proceeding (such as a trial) to prove a fact in issue based on the object's physical characteristics.
The two types of evidence at crime scenes:
Biological evidence (e.g., blood, body fluids, hair and other tissues)
Latent print evidence (e.g., fingerprints, palm prints, footprints)
The biggest impediment to an investigation is the removal or loss of a piece of evidence from the scene of a crime.
Hence, at any crime scene, the two greatest challenges to the physical evidence are contamination and loss of continuity.
Learn more about the physical evidence here:
brainly.com/question/13505766
#SPJ1
Explanation:
It is given that,
Focal length of the concave mirror, f = -13.5 cm
Image distance, v = -37.5 cm (in front of mirror)
Let u is the object distance. It can be calculated using the mirror's formula as :
![\dfrac{1}{v}+\dfrac{1}{u}=\dfrac{1}{f}](https://tex.z-dn.net/?f=%5Cdfrac%7B1%7D%7Bv%7D%2B%5Cdfrac%7B1%7D%7Bu%7D%3D%5Cdfrac%7B1%7D%7Bf%7D)
![\dfrac{1}{u}=\dfrac{1}{f}-\dfrac{1}{v}](https://tex.z-dn.net/?f=%5Cdfrac%7B1%7D%7Bu%7D%3D%5Cdfrac%7B1%7D%7Bf%7D-%5Cdfrac%7B1%7D%7Bv%7D)
![\dfrac{1}{u}=\dfrac{1}{(-13.5)}-\dfrac{1}{(-37.5)}](https://tex.z-dn.net/?f=%5Cdfrac%7B1%7D%7Bu%7D%3D%5Cdfrac%7B1%7D%7B%28-13.5%29%7D-%5Cdfrac%7B1%7D%7B%28-37.5%29%7D)
u = -21.09 cm
The magnification of the mirror is given by :
![m=\dfrac{-v}{u}](https://tex.z-dn.net/?f=m%3D%5Cdfrac%7B-v%7D%7Bu%7D)
![m=\dfrac{-(-37.5)}{(-21.09)}](https://tex.z-dn.net/?f=m%3D%5Cdfrac%7B-%28-37.5%29%7D%7B%28-21.09%29%7D)
m = -1.77
So, the magnification produced by the mirror is (-1.77). Hence, this is the required solution.
C is correct. Only a closed circuit can carry current, opening a switch disconnects the circuit and stops current from flowing. Remember, all current flows in loops, if you can't make a loop out of it, current can't flow, and opening a switch, assuming no other paths for current exist, will completely stop the current.