A 60 $$\mu$$F parallel plate capacitor whose plates are separated by 6 mm is charged to 250 V, and then the charging source is removed. When a slab of dielectric constant 5 and thickness 3 mm is placed between the plates, find the change in the potential difference across the capacitor.
Four capacitors with capacitances $$C_1=l \propto \mathrm{F}, C_2=1.5 \propto \mathrm{F}, C_3=2.5 \propto \mathrm{F}$$ and $$C_4=0.5 \propto \mathrm{F}$$ are connected as shown and are connected to a $$30 \mathrm{~V}$$ source. The potential difference between points $$a$$ and $$b$$ is
In the given circuit, if the potential difference between A and B is 80 V, then the equivalent capacitance between A and B and the charge on 10 $$\propto$$ F capacitor respectively, are
