**Capacitance Equation:**

C=Q/V

Where,

- C=Capacitance in Farads (F).
- Q=Electrical Charge in Coulombs.
- V=Voltage in Volts.

**Capacitance (C):** Capacitance is the amount of electric charge moved in the condenser (Capacitor), when one volt power source is attached across its terminal.

- It serves the purpose of outer most cover of the dc machine. so that the insulating material get protected from the harmful atmospheric environmental like noise, dust and various gases like SO2, acidic fumes etc.
- It provides mechanical support to the poles.
- It forms a part of the magnetic circuit.
- It provides a path of low reluctance for magnetic flux.
- It is prepared by using cast iron. For large machines, rolled steel, cast steel, silicon steel is used which provides high permeability.

**Working and Construction of a capacitor :**

Whenever voltage is applied across its terminals, (Also known as charging of a capacitor) current start to flow and continue to travel until the voltage across both the negative and positive (Anode and Cathode) plates become equal to the voltage of the source (Applied Voltage). These two plates are separated by a dielectric material (such as mice, paper, glass, etc. which are insulators), which is used to increase the capacitance of the capacitor.

When we connect a charged capacitor across a small load, it starts to supply the voltage (Stored energy) to that load until the capacitor fully discharges.

Capacitor comes in different shapes and their value is measured in farad (F). Capacitors are used in both AC and DC systems

As current flows along a wire,the magnetic field rotates in the direction of a corkscrew.

A generating action requires following basic components to exits

- The conductor or a coil.
- The flux.
- The relative motion between conductor and flux.

If the series current gets double then, the resistance is halved.

In an electric circuit, it is often convenient to have a voltage source rather than a current source (e.g. in mesh analysis) or vice versa. This is made possible using source trformations. It should be noted that only practical voltage and current sources can be trformed.

In other words, a Th´evenin’s equivalent circuit is trformed into a Norton’s one or vice versa. The parameters used in the trformation are given as follows.

Th´evenin parameters: VTH ,RTH =⇒ RN = RTH ,IN = VTH/RTH.

Norton parameters: IN ,RN =⇒ RTH = RN ,VTH = RN IN.

Any load resistance, RL will have the same voltage across, and current through it when connected across the terminals of either source.

1/2 C V2 Joules where C is in farads and V in volts.

To reverse direction of rotation of dc motor, either direction of main field produced by the field winding is reversed or direction of the current passing through the armature is reversed.

By changing the direction of current passing through the field winding,the direction of the main field can be reversed.

F = [2 I2 / d] 10

Newtons/meter where I is in amps and d is in meters With currents in opposite directions, the force is pushing the conductors apart.

Energy stored =1/2 L I2 Joules where L is in henries and I is in amps.

The Main Difference between Active and Passive Components

**Active Components: **Those devices or components which produce energy in the form of Voltage or Current are called as Active Components

For Example: Diodes Tristors SCR etc…

**Passive Components: **Those devices or components which store or maintain Energy in the form of Voltage or Current are known as Passive Components

For Example: Resistor, Capacitor, Inductor etc…

The ratio of rms value to average value of an ac quantity is called form factor.

**Form Factor = RMS value/ Average value**

The ratio of maximum value to the RMS value of an ac quantity is called as peak factor.

**Peak Factor = Maximum Value/RMS value**

If the resistance total in a series circuit doubles the current will reduce to half.

W = I2 R = V2 / R.

Motors obey the left hand rule and generators the right hand rule.

Role of Capacitor in AC Circuits: In an AC circuit, capacitor reverses its charges as the current alternates and produces a lagging voltage (in other words, capacitor provides leading current in AC circuits and networks).

Role and Performance of Capacitor in DC Circuit.

In a DC Circuit, the capacitor once charged with the applied voltage acts as an open switch.

If it is decided the current rating and already cable installed according to the rating of final sub circuit. and we want to know that how many light point will be on this final sub circuit.

Suppose for a normal lighting in a home,office or hall, the current rating of sub circuit or final sub circuit is 5Amp and supply Voltage is 220 Volts. then how many 100 Watt Lamps we can instal on that specific sub circuit. We can find the number of lamps by using this formula.

It is necessary that maximum area of the armature comes across the flux produced by the field winding.

Pole shoe enlarges the area of armature core to come across the flux, which is necessary to produce larger induced emf. To achieve this, pole shoe has been given a particular shape.

Pu11= B2 107 / (8 ) Newtons per m2 of magnet force where B is in tesla.