In wheatstone's bridge P=9 ohm, R=4 ohm and S=6 ohm. How much resistance must be put in parallel to the resistance S to balance the bridge?
An electrician has 2 resistor coil. He can obtain resistance 3 ohm, 4 ohm, 12 ohm and 16 ohm by keeping them alone and by connecting them in series and parallel. The resistance of these coils are how much in ohms?