World of Physical Science

   HEATING EFFECT OF ELECTRIC CURRENT      We know that a battery or a cell is a source of electrical energy. The chemical reaction within the cell generates the potential difference between its two terminals that sets the electrons in motion to flow the current through a resistor or a system of resistors connected to the battery. We have also seen that to maintain the current, the source has to keep expending its energy. Where does this energy go? A part of the source energy in maintaining the current may be consumed into useful work (like in rotating the blades of an electric fan). Rest of the source energy may be expended in heat to raise the temperature of gadget. We often observe this in our everyday life. For example, an electric fan becomes warm if used continuously for longer time etc. On the other hand, if the electric circuit is purely resistive, that is, a configuration of resistors only connected to a battery; the source energy continually gets dissi...

CIRCUIT DIAGRAM     We know that an electric circuit comprises a cell (or a battery), a plug key, electrical component(s), and connecting wires. It is often convenient to draw a schematic diagram, in which different components of the circuit are represented by the symbols conveniently used. Conventional symbols used to represent some of the most commonly used electrical components are given in Table below- PICTURE:-1      The electronic circuit symbols mainly involve wires, power supplies, resistors, capacitors, diodes, transistors, meters, switches, sensors, logic gates, audio devices, and other components. PICTURE:- 2 OHM’S LAW      Is there a relationship between the potential difference across a conductor and the current through it? Let us explore with an Activity. In 1827, a German physicist Georg Simon Ohm (1787–1854) found out the relationship between the current I, flowing in a metallic wire and the potential difference across its te...