Chapter 12 Electricity and Circuits

(i) Switch                                                                                                                                                                                                                                      Switch is the device which is used to break or continue the electric current.  

(ii) Two                                                                                                                                                                                                                                                   An electric cell has two terminals: Positive or Negative.

(a) True

Because metals are good conductor of electricity.

(b) False

It is false because jute is an insulator of electricity, so we cannot use this.

(c) False

This statement is false because thermocol is the insulator of electricity.

The bulb would not glow in this arrangement because, the terminals of the bulb are connected to the insulator part (plastic) to the screw driver. Here the circuit is not complete. For the bulb to glow, there must be a conductor that will be connected to the electric cell. 

Here, the free ends of the wires should be connected to the bulb to complete the circuit.

Electric switch is a device which is used to break or to continue the electricity in electricity circuit. It is easy to handle electricity used easily with the help of an electric switch.

Some electrical gadgets that have switch built into them are freeze, microwave, toasters etc.

The objects through which electricity can pass easily are called conductors and other one from which electricity cannot pass through them are called insulators. For a bulb to glow, there should be presence of conductors. Here bulb is not glowing if we use an eraser at the place of pin because eraser is an insulator of electricity. So, here circuit is not complete, so the bulb will not glow.

The bulb would not glow in the circuit because here the electric circuit is not complete. For the bulb to glow, circuit must be complete so that electric current pass through it. A glowing bulb shows that there current is flowing from the positive terminal of the battery to the negative terminal.

Diagram:

Using, the “conductor tester” on an object. It was found that the bulb begins to glow, then it must be conductor. Conductors are those from which electricity can pass through easily. To complete an electric circuit, a battery should be connected to the conductor material. So, here the bulb begins to glow.

An electrician use rubber gloves while repairing an electric switch at home because rubber is the insulator of electricity. It protects the electrician from the electric shock. So the electrician use rubber gloves.

The handles of the tools like screw driver and pliers used by electrician for the repairing usually contains plastic or rubber covers on them because plastic or rubber both are the insulators of the electricity. Covering of the plastic or rubber on the tools helps the electrician to repair easily because using covered tools protect them from an electric shock.