JNTU B.Tech II FUNDAMENTALS OF ELECTRICAL ENGINEERING Previous Question Paper (October - 2020 - R13)

To find the current i in a bridge network, first identify the circuit configuration. If the bridge is balanced, the ratio of opposite arms is equal, and the current through the central branch is zero. If unbalanced, apply Kirchhoff's Laws or perform a Delta-to-Wye (Δ-Y) transformation to simplify the circuit into a series-parallel combination.

1. Identify nodes and loops: Assign currents to each branch and apply Kirchhoff's Current Law (KCL) at each junction.

2. Apply Kirchhoff's Voltage Law (KVL): Write loop equations for the independent meshes. For a bridge with resistances R1, R2, R3, R4 and a central resistance R5, the KVL equations are:

3. Solve for currents: Use Cramer's rule or substitution to solve the system of linear equations for the branch currents. The current i is the algebraic sum of the currents flowing through the specific branch of interest.

Faraday's laws describe the induction of electromotive force (EMF) in a conductor due to a changing magnetic field.

First Law: Whenever the magnetic flux linked with a circuit changes, an EMF is induced in it. This EMF lasts only as long as the change in flux continues.

Second Law: The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux linkages. Mathematically, this is expressed as:

Where e is the induced EMF, N is the number of turns in the coil, and dΦ/dt is the rate of change of magnetic flux. The negative sign, known as Lenz's Law, indicates that the induced EMF acts in a direction that opposes the change in flux that produced it.