Anannya responded to the question: Why do electrical appliances with metallic bodies are connected to the mains through a three pin plug, whereas an electric bulb can be connected with a two pin plug?
She wrote: Three pin connections reduce heating of connecting wires.
(i) Is her answer correct or incorrect? Justify.
(ii) What is the function of a fuse in a domestic circuit?

Assertion : Electric applicances with metallic body, e.g. heaters, presses etc, have three pin connections, whereas an electric bulb has a two pin connection. Reason : Three pin connection reduce heating of connecting cables.

Assertion (A): Electric appliance with metal body has three electrical connections. But an electrical bulb has two electrical connection. Reason (R ): Three pin connection reduces chances of electrical shocks.

Raman is a student of class X. Raman's mother was making tea in an old electric kettle having metal case. She switched on the power supply to the electric kettle. When Raman's mother touched the metal case of working electric kettle unknowingly, she got a severe electric shock. Raman put off the main switch quickly. After removing the kettle plug from socket, Raman found that the connecting cord was torn where it touched the metal case of the kettle. He also found that though the red and black wires of connecting cord were firmly connected to the two lower terminals of the power plug but the green wire of cord was not connected to the upper terminal of the plug. Raman replaced the torn connecting cord and also connected the three wires fo cord firmly to the power plug terminals. (a) Why did Raman put off the main switch quickly ? (b) What name is given to (i) red wire (ii) black wire, and (iii) green wire, of the connecting cord ? (c) Which wire, red, black or green, touched the metal case of electric kettle when Raman's mother got electric shock ? (d) Which safety device was not working in electric kettle circuit which could have prevented the electric shock ? (e) What values are displayed by Raman in this incident ?

The table below shows the current in three different electrical appliances when connected to the 240V mains supply: {:("Appliance","Current"),("Kettle",8.5A),("Lamp",0.4A),("Toaster",4.8A):} (a) Which appliance has the greatest electrical resistance? How does the data show this? (b) The lamp is connected to the mains supply by using a thin, twin-cored cable consisting of live and neutral wires. State two reasons why this cable should not be used for connecting the kettle to the mains supply. (c) Calculate the power rating of the kettle when if is operated from teh 240V mains supply. (d) A man takes the kettle abroad where the mains supply is 120V. What is the current in the kettle when it is operated from the 120 supply?

In a household electric circuit different appliances are connected in parallel on one another . Give two reasons. An electrician puts a fuse of rating 5 A in that part of domestic electricity ciruit in which an electric heater of rating 1.5 K W, 220 V is operating. What is likely to happen in this case and why? What change , if any, needs to be made?

Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit, another set of three bulbs of the same wattage are connected in parallel to the same source. (a) Will the bulbs in the two circuits glow with the same brightness ? Justify your answer. (b) Now let one bulb in both circuits get fused. Will the rest of the bulbs continue to glow in each circuit ? Give reason. (a) In a household electric circuits, different appliances are connected in parallel to one another. Give two reasons for the same. (b) An electrican puts a fuse of rating 5 A in that part of domestic electrical circuit in which electrical heater of rating 1.5 kW, 220 V is operating. What iis likely to happen in this case and why ? What change, if any, needs to be made ?