# Boon or Bane

Pages: 11 (1820 words) Published: May 31, 2013
Class X, PHYSICS, "Electricity"
Definitions

1. Insulators

Those material objects that do not allow charge to pass through them are known as Insulators or non-conductors.

2. Conductors

Those material objects that allow the charge to pass through them are called conductors.

3. Semi Conductors

Those material objects that allow some charge to pass through them are called Semi-Conductors.

4. Free Electron

Those electrons that are loosely bound by their atom and can move freely within the material are called free electrons.

5. Dielectric

The medium or space (vacuum) between two charges is said to be dielectric.

6. Force of Attraction

When two charges attract each other the force is called force of attraction. It has a negative sign.

7. Force of Repulsion

When two charges repel each other the force is called force of repulsion. It has a positive sign.

8. Equivalent Resistance

The relative resistance that has equal value to the combined value of a resistor of a circuit is called equivalent resistance. It is denoted by R(E).

9. Direct Current

Such a current that does not change its direction is known as direct current. It is denoted by DC, which is obtained from primary and secondary cells.

10. Alternating Current

Such a current that reverses its direction with a constant frequency from positive to negative and negative to positive direction is known as Alternating Current, obtained by generators. It is denoted by AC.

11. Conventional Current

An electric current considered to flow from points at positive terminal potential to points at negative potential.

12. Primary Cell

A voltaic cell in which the chemical reaction that produces the e.m.f is not reversible is known as Primary Cell.

13. Secondary Cell

An electric cell that can be changed by passing an electric current through it is called Secondary Cell. The chemical reaction in this case is reversible.

14. Fused Plug

It is a wired plug, which has its own cartilage fuse. It is used in a ring main circuit.

15. Electric Circuit

A combination of electrical components that form a conducting path is called an electric circuit.

16. Commercial Unit of Energy (kWh)

1 kWh is the energy produced by a resistor or conductor in 1 hour when it uses 1000 Watt power.

17. Watt

If 1 joule of electrical work is done in 1 second then the power is called 1 watt.

Electrostatic Induction

When a charged body brought close to another uncharged body then other body gains some chrge without any touch. This is called electrostatic induction.

Gold Leaf Electroscope

An electroscope is a device that can be used for detection of charge.

Construction

It consists of a glass case that contains two turn leaves of gold (Au) which are capable to diverge. The leaves are connected to a conductor to a metal ball or disk out side the case, but are insulated from the case itself.

Working

If a charged object is brought close to the ball, a separation of charge is induced between the ball and gold leaves. The two leaves become charged and repel each other. If the ball is charged by touching the charged object the whole assembly of ball and leaves acquires the same charge. In either case greater the amount of charge greater would be the diverging in lens.

Electrostatic Potential

A charged body place in electrostatic field as an electrostatic potential as earth has its gravitational potential.

Potential Difference

Definition

“The difference in electrostatic potential between two points in an electrostatic field is called potential difference.”

When a unit positive charge body moves against an electrical field from A to B, then work done has been stored as potential difference. Therefore, we say that

“Potential difference is work done or energy stored per unit charge.”

Unit

Since

Potential Difference = Work Done/Charge
V = W/q
Therefore, its unit is:
V = Joules/Coulomb =...