Test: Electricity - 3

The electric field is the region around a charged particle where the lines of force can be felt by another charge by getting repulsed or attracted as per their sign of charges.

Electric Field Intensity (E)

The electrostatic force acting per unit positive charge on a point in electric field is called electric field intensity at that point.

Electric field intensity E =

Electric potential 
An electric potential is defined as the amount of electric potential energy that a unitary point electric charge would have if located at any point of space.

Note:
Electric potential is equal to the work done by an electric field in carrying a unit positive charge from infinity to that point.

Potential difference is the difference in electric potential energy between two points. It is the amount of work done in moving a unit positive charge from one point to another point in an electric field. This is measured in volt. 

Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current orelectrical discharge.

Current is defined as amount of electric charge flowing through a cross section of circuit in unit time I=Q/T

A  negatively charged conductor has negative potential less than that of the earth.The electric potential difference between two points in an electric circuit is the work done in moving a unit positive charge from one point to the other.

A voltmeter is an instrument used for measuring the electrical potential difference between two points in an electric circuit.

An electric current is a flow of electric charge. In electric circuits, this charge is often carried by electrons moving through a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionized gas (plasma)

Electric current is electric charge in motion. It can take the form of a sudden discharge of static electricity, such as a lightning bolt or a spark between your finger and a ground light switch plate. More commonly, though, when we speak of electric current, we mean the more controlled form of electricity from generators, batteries, solar cells or fuel cells

Conventional current or simply current, behaves as if positive charge carriers cause current flow. Conventional current flows from the positive terminal to the negative.

As the temperature of a metallic conductor increases, the kinetic energy of the electrons of the conductor also increases ,due to which more obstruction is offered to the flowing electrons and hence the current.Therefore,as more obstruction is offered to the flowing electrons, the resistance is increased.

Resistance increases with length because the electrons have further to go, so suffer greater collisions with atoms in the material.

The reason is adding resistors in parallel increases the effective cross sectional area of the circuit and As we know that resistance is inversely proportional to area of cross section.

Since electrons are negative they should be repelled by the negative charge and attracted by the positive charge, that is, in an electric field the electrons must move from regions of low potential to the regions with high potential by the action of the electrical forces.

Electrical resistivity of a given metallic wire depends on number density of free electrons in the conductor which is the nature of material

A positively charged subatomic particle that is housed within the nucleus.

A negatively charged subatomic particle that has negligible mass and moves around in a cloud around the nucleus.

Materials with high electron mobility (many free electrons) are called conductors, while materials with low electron mobility (few or no free electrons) are called insulators.