when and resistors of equal resistance are connected in series and parallel respectively then the ratio of their effective resistance is?

The fig. Shows a network of resistance in which the point A is earthed

When a p.d of 2v is applied across a resistor, 10j of energy are covered. What charge flows through the resistor?

Please provide it's solution. In video form Find the equivalent resistance of the given figure

The resistivity of material is 10 ohm m at 30 C when the temperature drops to 28 then the resistivitydrops by 2. The temperature coefficient of resistivity of material is

Three cells of 2.0v each and internal resistance of 1.0 each are connected in series and in parallel calculate the new emf and new internal resistance in each connection