Answer: f=150cm in water and f=60cm in air.
Explanation: Focal length is a measurement of how strong light is converged or diverged by a system. To find the variable, it can be used the formula:
= (nglass - ni)(
- 
).
nglass is the index of refraction of the glass;
ni is the index of refraction of the medium you want, water in this case;
R1 is the curvature through which light enters the lens;
R2 is the curvature of the surface which it exits the lens;
Substituting and calculating for water (nwater = 1.3):
= (1.5 - 1.3)(
- 
)
= 0.2(
)
f = 
= 150
For air (nair = 1):
= (1.5 - 1)( - )
f = 
= 60
In water, the focal length of the lens is f = 150cm.
In air, f = 60cm.
A compound optical microscope or just a optical microscope is a microscope that uses light and has more than one lens.
Density is equal to mass divided by volume; that said, you would divide 38.6 by 2 to get your answer
Answer: The forces of gravity
Explanation: The consequence of this phenomenon is that every mass exerts a so-called "force of mutual attraction" on every other mass. The attractive force that the celestial bodies exert on other masses by virtue of their total mass is called the force of gravity.
Hope this helps
Explanation :
We know that the resistance of the wire is given by :
Where
is the resistivity
l is the length of the wire
A is the area of the wire.
Another factor on which the resistance of wire depends is temperature. It is given by :
![R=R_{ref}[1+\alpha (T-T_{ref})]](https://tex.z-dn.net/?f=R%3DR_%7Bref%7D%5B1%2B%5Calpha%20%28T-T_%7Bref%7D%29%5D)
So, it is clear that the resistance of the wire is directly proportional to the temperature. It we want to decrease the resistance of the piece, its temperature should be decreased.
So, the correct option is (3) " decreasing the wire’s temperature ".
