For the given network the potential at point a can be found by applying KVL.
For loop 1
Va = E1 − I1R1
Va = I3R3
For loop 2
Va = E2 − I2R2
In the same way that we can have series, parallel or series-parallel electric circuits, we can also have equivalent series and series-parallel (but not parallel) magnetic circuits.
In practice, a magnetic circuit may consist of several parts in a series of different lengths, cross-sectional areas, and permeabilities. In such a series magnetic circuits, all the reluctances of several parts will get summed up together (as resistors in an electric circuit) to form the net reluctance of the circuit.
In series magnetic circuits the flux passing through each part will be the same (as current in the series electric circuits).
The difference in level between points of supports and the lowest point on the conductor is called sag.
When the conductor is suspended between two supports at some level, it takes the shape of a catenary. However, if the sag is very small compared with the span, then the sag-span curve is like a parabola.
The tension at any point on the conductor acts tangentially. Thus tension To at the lowest point O acts horizontally.
A practical parallel resonance circuit is represented by an inductance and a resistance id one branch and a capacitance in other branches.
At resonance in a practical parallel resonance circuit, the impedance is maximum. Hence, it is called a rejector circuit, and it exhibits the property of voltage magnification.
Z = L/CR
A single-phase induction motor with only one winding on the stator cannot produce any starting torque. Hence, some extra arrangement is required to start the motor. In the running condition, the motor is capable of developing the torque with only one winding on the stator.
The simplest method of starting is to provide an auxiliary winding on the stator in addition to the main winding. The two windings are placed in the stator with their axes displaced by 90 electrical degrees in space.