Electricity and Circuits
Exercises
- Fill in the blanks:
(a) A device that is used to break an electric circuit is called _ .
Ans:- Switch.
(b) An electric cell has __ terminals.
Ans:- Two.
- Mark ‘True’ or ‘False’ for following statements:
(a) Electric current can flow through metals.
Ans:- True.
(b) Instead of metal wires, a jute string can be used to make a circuit.
Ans:- False.
(c) Electric current can pass through a sheet of thermo Col.
Ans:-False.
- Explain why the bulb would not glow in the arrangement shown in Fig. 12.13.
Ans:- Cricket match bats have been used while making the said iron circuit. It is non-conductive of irony. So the bulb in the arrangement does not burn.
- What is the purpose of using an electric switch? Name some electrical gadgets that have switches built into them.
Ans:- Switch is used to disconnect or connect an electrical circuit.
Some of the electronic devices connected to switches are torches, irons, table fans, radios, televisions, tape recorders, etc.
- Would the bulb glow after completing the circuit shown in Fig. 12.14 if instead of safety pin we use an craser?
Ans:- Completing the circuit using pencil stain eraser instead of safety pin will not burn the bulb again. Because, a pencil stain eraser is a denominator of irony.
- Would the bulb glow in the circuit shown in Fig. 12.15?
Ans:- The circuit bulb shown in the said figure will light up. This is because in the figure the wire connected to the bulb is connected to the two poles positive and negative of the battery.
- Using the “conduction tester” (পৰিবাহিতা টেষ্টাৰ) on an object it was found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.
Ans:- The bulb was found to be burning as the conductivity tester was used in the case of an object. Generally, when the electric current through an object is driven, it is called a lightning conductor.
- Why should an electrician use rubber gloves (ৰবৰৰ হাতমোজা) while repairing an electric switch at your home? Explain.
Ans:- Vidya flows through the human body. But vidya does not flow through the rubber. That is why the electrician should wear gloves while repairing the switches etc. in the house. Because if the wind flows through him carelessly, it can also fall on the face of death.
- The handles of the tools like screwdrivers and plies used by electricians for repair work usually have plastic or rubber covers on them. Can you explain why?
Ans:- Devices such as screw-drivers, chapanas, etc., used by an electrician in repair work are usually made of iron or other metals. Vidyut flows through metals. On the other hand, electricity cannot flow through rubber or plastic products. Therefore, the tubes of the electric conductive metal are coated with iron-conducting rubber or plastic.