sowndharyaphysics

Resistance and Ohm’s Law Ohm’s Law The current flowing through an ohmic conductor is directly proportional to the applied potential difference between the two ends of the conductor. Ohm’s Law states the relationship between the potential difference across a conductor and the current through it Resistance Resistance is a measure of the opposition offered to the current flow in an electric circuit. Resistance is measured in ohms. All materials resist current flow up to some degree. All materials fall into one of two broad categories: Conductors and Insulators. Factors Affecting Resistance & How They Affect Resistance is: Directly proportional to the length of the conductor. Directly proportional to the nature of the conductor. Directly proportional to the temperature of the conductor. Inversely proportional to the cross-sectional area of the conductor. Resistivity The electrical resistance offered by a substance of unit length and unit cross-sectional area is called resistivity. h ρ ...

Atomic Structure An atom has a positively charged nucleus and negatively charged electrons revolving around it. Valence electrons in metals are free to move within the conductor and constitute an electric current. Charge The charge is an intrinsic property of matter by virtue of which it can exert electromagnetic force. Conductors and Insulators A substance which offers comparatively less opposition to the flow of current is known as a conductor, and substances which offer larger opposition are  called insulators. Some examples of conductors include copper, iron and steel. Some of examples of insulators include glass, dry wood and cotton. Electric Potential and Potential Difference The electric potential at a point is defined as work done in bringing a unit positive charge from infinity to that point. The potential difference between two points is defined as the difference in electric potentials at the two given points. The electrons move only if there is a difference in electric p...