Answer:
Part a)
V = 9 Volts
Part b)
[tex]\Delta V = 4.29 Volts[/tex]
Explanation:
Part a)
When capacitor plates are charged to a certain voltage then we have
[tex]\Delta V = 9 volts[/tex]
now battery is disconnected so here we have potential difference between the plates is given as
[tex]\Delta V = \frac{Q}{C}[/tex]
now we have charge conserved on the plates as well as the capacitance is also constant so here potential difference will remains the same
Part b)
Now the teflon sheet is inserted between the plates of capacitor
so capacitance of the capacitor will change by a factor of dielectric constant
So we will have
[tex]C' = kC[/tex]
[tex]k_{teflon} = 2.1[/tex]
so here we have new capacitance given as
[tex]C' = 2.1 C[/tex]
now the voltage difference will be given as
[tex]\Delta V = \frac{Q}{2.1C}[/tex]
[tex]\Delta V = \frac{9.00}{2.1}[/tex]
[tex]\Delta V = 4.29 Volts[/tex]