Gauss's law helps in

Charge on the outer sphere is $$q$$ and the inner sphere is grounded. The charge on the inner sphere is $$q^{\prime}$$, for $$\left(r_2 > r_1\right)$$. Then,

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 a potentiometer of 10 wires, the balance point is obtained on the 6th wire. To shift the balance point to 8th wire, we should