Author: workhouse123

The electrical resistance generally changes with the change of temperature. The resistance does not only increase with the rise in temperature but it also decreases in some cases. In fact, the increase or decrease in resistance with the rise in temperature depends on the nature of the resistance material discussed as follows:

Ohm’s law cannot be applied to the non-linear clients such as circuits containing electronic tubes or transistors and the circuits used to produce electric arc. Example 1.1 The specific resistance of platinum at 0°C is 10.5 microohm cm. What should be the length of platinum wire of No. 32 S.W.G. (diameter = 0.0274 cm) to have a…

Ohm’s law states that the current flowing between any two points of a conductor (or circuit) is directly proportional to the potential difference across them, as shown in Figure 1.8, provided physical conditions i.e. temperature etc. do not change. Fig. 1.8  Potential difference (voltage) applied across a wire having resistance R ohm Mathematically I ∝ V or In other words,…

The amount of energy supplied by the source to each coulomb of charge is known as emf of the source, whereas the amount of energy used by one coulomb of charge in moving from one point to the other is known as potential difference between the two points. For instant, consider a circuit as shown in Figure 1.7.…

When an electric potential difference is applied across the metallic wire, the loosely attached free electrons, as shown in Figure 1.3, start drifting towards the positive terminal of the cell (see Fig. 1.4). This continuous drifting of electrons constitutes the electric current. Therefore, a continuous drifting of electrons in an electric circuit is called electric current. Fig.…

The capacity of a charged body to do work is called electric potential. Obviously, the measure of electric potential is the work done to charge a body to one coulomb, that is, Electric potential  Unit: Since work done is measured in joule and charge in coulomb, the unit of electric potential is joule/coulomb or volt.

The valance electrons that are very loosely attached to the nucleus of an atom and can be easily detached are called free electrons. These free electrons are so loosely attached to the nucleus that they do not know the atom to which they belong originally. Thus, they move from one atom to the other at…

The charge on an electron is very small, and it is not convenient to take it as the unit of charge. Therefore, coulomb2 is used as the unit of charge in practice. Hence, the practical unit of charge is coulomb.   1 coulomb = charge on 628 × 1016 electrons   If a body is said to…

Every substance or body is electricity neutral as all the atoms of the body contain equal number of electrons and protons. Fig. 1.2  Charged bodies (a) Positively charged body(b) Negatively charged body However, when some electrons are detached from the body, a deficit of electrons occurs. As a result, the body attains positive charge [Fig. 1.2(a)],…

It has been observed that every matter is electrical in nature, since it contains charged particles such as protons and electrons. Therefore, the following points are observed: