Answer:
Part a)
[tex]V' = 7.77 Volts[/tex]
Part b)
[tex]k' = 6.27 [/tex]
Explanation:
As we know that capacitor plate is connected across 2.1 V and after charging it is disconnected from the battery
So here we can say that charge on the plates will remain conserved
So we will have
[tex]Q = kC(2.1)[/tex]
now dielectric is removed between the plates of capacitor
so new potential difference between the plates
[tex]V' = \frac{Q}{C'}[/tex]
[tex]V' = \frac{kC(2.1)}{C}[/tex]
[tex]V' = 3.7 \times 2.1 [/tex]
[tex]V' = 7.77 Volts[/tex]
Part b)
Now the capacitor plates are again isolated and unknown dielectric is inserted between the plates
So again charge is same so potential difference is given as
[tex]V" = \frac{Q}{k'C}[/tex]
[tex]0.59 V = \frac{kCV}{k'C}[/tex]
[tex]0.59 = \frac{3.7}{k'}[/tex]
[tex]k' = 6.27 [/tex]