What is the name of thin wire in the electric bulb?
Filament.
In any electric circuit, when the switch is on and the current flows through it why do the wire, switches, bulb or devices become hot?
Fill in the blanks:
(a) A device that is used to break an electric circuit is called_______________
(b) An electric cell has___________
Name the scientist who invented electric cell and the scientist who invented electric bulb.
The handles of the tools like screwdrivers and pliers used by electricians for repair work usually have plastic or rubber covers on them. Can you explain why?
Mark ˜True' or ˜False' for the following statements:
(a) Electric current can flow through metals.
(b) Instead of metal wires, a jute string can be used to make a circuit.
(c) Electric current can pass through a sheet of thermocol.
What is the purpose of using an electric switch? Name some electrical gadgets that have switches built into them.
If you touch an electric wire carrying current you get a shock, but if on the same wire the birds sit they do not get any shock/current. Explain why?
The headlights of a car have reflectors behind the bulb. What is the function of reflectors?
Mark ˜True' or ˜False' for the following statements:
(a) Electric current can flow through metals.
(b) Instead of metal wires, a jute string can be used to make a circuit.
(c) Electric current can pass through a sheet of thermocol.
Why should an electrician use rubber gloves while repairing an electric switch at your home? Explain.
Would the bulb glow after completing the circuit shown in Fig. 12.9 if instead of safety pin we use an eraser?
Using the"conduction tester” on an object it was found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.
Complete the drawing shown in Fig. 12.9 to indicate where the free ends of the two wires should be joined to make the bulb glow.
(1)What is electric circuit?
(2)How many types of electric circuit are there? Define them.
(3)Draw a diagram to show the closed circuit for switch, bulb and dry cell.
Identify conductors and insulators from the following:Eraser, paper, matchstick, copper wire, pencil lead, polythene