MAGNETISM AND ELECTROMAGNETISM MA GNET A brown coloured stone which is found naturally on earth's surface

6.1. MAGNET

A brown coloured stone which is found naturally on earth's surface is called magnetite (Fe₃O₄) or magnet. First of all such stone was found in the city called Magnesia (in Asia), hence it was given the name magnetite. Later on, the word magnetite was reduced to magnet. In India, it is found in Tamilnadu and Orissa states. The properties of a magnet are called magnetism.

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CELL AND BATTERY INTRODUCTION A cell is a device which converts chemical energy into electrical energy.

5.1. INTRODUCTION

A cell is a device which converts chemical energy into electrical energy. There are two main types of cells — (1) primary (2) secondary.

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RESISTORS INTRODUCTION All materials oppose the flow of current through them, i e , they have resistance.

4.1. INTRODUCTION

All materials oppose the flow of current through them, i e , they have resistance. When a wire or a piece of a material is used as a component for producing resistance in a circuit. It is called a resistor.  Resistors used in electronic equipments are classified as under on the basis of their construction : carbon, wire wound, ballast, PTC, NTC, varistor, LDR, etc.

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RESISTANCE Introduction All material offer a little or more opposition to the, flow of electric current through them

3.1. INTRODUCTION

All material offer a little or more opposition to the, flow of electric current through them, this property of material is termed as resistance. Its symbol is R and its unit is ohm (Ω). The resistance of a material is not affected by the direction of flow of current, hence it remains the same on D.C. and A.C. course, a difference exists in the electric consumption on D.C. and A.C. of a conductor.

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