JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (August/September - 2022 - R13)

To determine the currents through R1 and R2, one must apply Kirchhoff's Laws or circuit reduction techniques based on the provided circuit diagram. If the resistors R1 and R2 are in parallel with a voltage source V, the current through each is calculated using Ohm's Law: I1 = V / R1 and I2 = V / R2. If they are in series with a source, the total resistance is R_total = R1 + R2, and the current I = V / (R1 + R2) flows through both. For more complex networks, nodal analysis or mesh analysis is employed to solve for the specific branch currents by setting up a system of linear equations based on the circuit configuration.

The Permanent Magnet Moving Coil (PMMC) instrument operates on the principle of the electromagnetic effect, specifically the force exerted on a current-carrying conductor placed in a magnetic field. When current flows through the moving coil, it experiences a mechanical force F given by the formula:

where N is the number of turns, B is the magnetic flux density, I is the current, and L is the length of the conductor. This force creates a torque that causes the coil to rotate against the restoring torque provided by control springs. The deflection of the pointer is directly proportional to the current flowing through the coil, resulting in a linear scale. The instrument also utilizes eddy current damping to bring the pointer to a steady position quickly without excessive oscillation.