Fire trucks have the word FIRE written two ways, as seen here, on the front of the truck. Why is that?
2 answers:
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a)
b)
c)
Explanation:
a)
The energy stored in a capacitor is given by
where
C is the capacitance of the capacitor
V is the potential difference across the plates of the capacitor
For the capacitor in this problem, before insering the dielectric, we have:
is its capacitance
V = 22.0 V is the potential difference across it
Therefore, the initial energy stored in the capacitor is:
b)
After the dielectric is inserted into the plates, the capacitance of the capacitor changes according to:
where
k = 3.55 is the dielectric constant of the material
C is the initial capacitance of the capacitor
Therefore, the energy stored now in the capacitor is:
where:
is the initial capacitance
V = 22.0 V is the potential difference across the plate
Substituting, we find:
C)
The initial energy stored in the capacitor, before the dielectric is inserted, is
The final energy stored in the capacitor, after the dielectric is inserted, is
Therefore, the change in energy of the capacitor during the insertion is:
So, the energy of the capacitor has increased by