Density d=m/V
mass m=d.V=13.5×5=67.5g
m=67.5g
hope this helps you
the less porous, the less permeable
Answer:
the field at the center of solenoid 2 is 12 times the field at the center of solenoid 1.
Explanation:
Recall that the field inside a solenoid of length L, N turns, and a circulating current I, is given by the formula:
Then, if we assign the subindex "1" to the quantities that define the magnetic field (
) inside solenoid 1, we have:

notice that there is no dependence on the diameter of the solenoid for this formula.
Now, if we write a similar formula for solenoid 2, given that it has :
1) half the length of solenoid 1 . Then 
2) twice as many turns as solenoid 1. Then 
3) three times the current of solenoid 1. Then 
we obtain:

Answer:
The value is 
and

Explanation:
From the question we are told that
The image distance is 
The focal length is 
From the lens equation we have that

=> 
=> 
Generally the magnification is

=> 
=> 