Ohm's law can be expressed in a mathematical form:

V=IR

Where: V = voltage expressed in Volts
I = current expressed in Amps
R = resistance expressed in Ohms

The formula can be manipulated so that if any two quantities are known the third can be calculated.

I=V/R

The transformation ratio is defined as the ratio of the secondary voltage to primary voltage. It is denoted by the letter K and is equal to the ratio of the number of turns in the secondary winding to the number of turns in the primary winding, if leakage flux is neglected

A half wave rectifier is a type of circuit that is used to convert alternating current (AC) power into direct current (DC) power.Only half the sine wave of the AC current passes through it and is converted to DC.

A half wave rectifier uses a single diode which effectively cuts off the sine wave at anything below 0 Volts, resulting in a single direction flow of the circuit in a stuttering pattern that omits the negative flow. Half wave rectifiers are sometimes used for AM radio transmission, but are not considered ideal for conversion purposes since half the power output is in effect wasted.

For a positive charge, the electric lines of force will be radially outward, and for a negative one, they will be radially inward.

Also, electric lines of force originate from a positive charge and terminate at a negative charge.

Thus, if we consider that a single line of force emerges out of a positive charge and loops back to the same point from where it originated, it would mean that there are two charges placed exactly at a same point, which is nonsensical.

Also, an electric line of force represents the direction in which a unit positive charge would move if placed along the line. So, in this case the positive charge should be repelled and then should come back towards the source charge, which would not be digestible.

A solar cell is an electronic device that catches sunlight and turns it directly into electricity. It's about the size of an adult's palm, octagonal in shape, and colored bluish black. Solar cells are often bundled together to make larger units called solar modules, themselves coupled into even bigger units known as solar panels (the black- or blue-tinted slabs you see on people's homes—typically with several hundred individual solar cells per roof) or chopped into chips (to provide power for small gadgets like pocket calculators and digital watches).

Silicon is the stuff from which the transistors (tiny switches) in microchips are made—and solar cells work in a similar way. Silicon is a type of material called a semiconductor. Some materials, notably metals, allow electricity to flow through them very easily; they are called conductors. Other materials, such as plastics and wood, don't really let electricity flow through them at all; they are called insulators. Semiconductors like silicon are neither conductors nor insulators: they don't normally conduct electricity, but under certain circumstances we can make them do so.

A solar cell is a sandwich of two different layers of silicon that have been specially treated or doped so they will let electricity flow through them in a particular way. The lower layer is doped so it has slightly too few electrons. It's called p-type or positive-type silicon (because electrons are negatively charged and this layer has too few of them). The upper layer is doped the opposite way to give it slightly too many electrons. It's called n-type or negative-type silicon. (You can read more about semiconductors and doping in our articles on transistors and integrated circuits.)

When we place a layer of n-type silicon on a layer of p-type silicon, a barrier is created at the junction of the two materials (the all-important border where the two kinds of silicon meet up). No electrons can cross the barrier so, even if we connect this silicon sandwich to a flashlight, no current will flow: the bulb will not light up. But if we shine light onto the sandwich, something remarkable happens. We can think of the light as a stream of energetic "light particles" called photons. As photons enter our sandwich, they give up their energy to the atoms in the silicon. The incoming energy knocks electrons out of the lower, p-type layer so they jump across the barrier to the n-type layer above and flow out around the circuit. The more light that shines, the more electrons jump up and the more current flows.

This is what we mean by photovoltaic—light making voltage—and it's one kind of what scientists call the photoelectric effect.

Earthing means connecting to the dead component (to the part that does not carry current) under normal conditions to the earth. Grounding means connecting the live part, it means the constituent that carries current under normal condition to the earth.