electricity || What is polarization? How do you remove this defect?

Electricity

What is electricity? Mention its type.

Ans:The continuous flow of electrons is called an electricity. It is of two type:

•  Static electricity
•  Current electricity

What are static electricity and current electricity? Write with example.
Ans:The electricity in which electric charges do not flow or remain at rest is called static electricity. The charge produced on comb, glass rod etc are examples of it.
The electricity in which electric charges flow is called current electricity e.g. current through copper wire.

How does a comb rubbed with hair attract pieces of paper? Explain it.
Ans: When we rubbed a comb into our hair then electrons of the atoms of the hair are transferred to the comb so that comb becomes negatively charged. When, this comb is brought near to pieces of paper, positive charges accumulate at the edge of paper. As opposite charges attract, comb starts to attract pieces of paper.

How are charges produced?
Ans:Charges are produced through friction between any two dry materials. Whether a body gets charged positively or negatively, it depends upon the nature of a body.

What are the sources of electricity?
Ans:The sources through which electricity can be generated are called sources of electricity. For example;

•  Cell
•  Dynamo/Generator
•  Photo Cell, etc

What is cell? Or what is electric cell?
Ans:A cell is a device which converts chemical energy into electrical energy.

What do you mean by simple cell or voltaic cell?
Ans:A simple cell is a cell having two metallic plates dipped in a acid solution to generate electricity.

What are electrodes?
Ans:The metal rods which are dipped in acid solution in a cell are called electrodes.

What is an electrolyte?
Ans:An electrolyte is a solution which splits into its constituents ions when electricity is passed.

What are anode and cathode?
Ans:Electrode with negative terminal is called cathode where as electrode with positive terminal is called anode.

What are the two defects of simple cell?
Ans:The following are the two defects of simple cell: 

• Polarization and
•  Local action 

What is polarization? How do you remove this defect?
Ans:During chemical reaction in a cell, hydrogen gas is produced and accumulates such defect is called polarization.
Polarization defect can be removed by using depolarizer like manganese dioxide, potassium dichromate etc.


What is local action? How do you remove this defect?
Ans:Zinc plate used in simple cell is not pure so impurities present in it provides a conducting path for the flow of charge. This makes the zinc wasted. This is called local action.
Local action can be removed by using pure zinc or amalgamated zinc rod.


What is the effect of local action in simple cell?
Ans:Local action in simple cell reduces the life of the cell.


Simple cell is not used to produce current for a long time, why?
Ans:Simple cell is not used to produce current for a long time because of the defects like polarization and local action.

What is dry cell?
Ans:A cell which has paste or powder chemicals and convert chemical energy into electrical energy is called dry cell.

Write the difference between simple cell and dry cell.
Ans:Difference between Simple cell and dry cell are:

S.no	Simple Cell	Dry Cell
1	It has liquid chemicals filled in a vessel.	It has dry chemicals.
2	Zinc plate is negative terminal and copper plate is positive terminal.	Carbon rod is positive and zinc is negative terminal.

 

Dry cell is more useful than simple cell in our daily life write with reasons.
Ans:Simple cell has liquid chemicals and difficult to carry from one place to another. Dry cell has no solution. So it is easy to carry and handle. Hence, there is no risk of spilling acid from dry cell. Thus, dry cell is more useful than simple cell in our daily life.


Why polarization not occured in dry cell?
Ans:Dry cell contains manganese dioxide inside it which acts as depolarizer. Hence, polarization is prevented.

Write some uses of cells.
Ans:Cells are widely used in torch-lights, radio, telephone, circuits, electric bells, etc.

What are the advantgaes of dry cell over simple cell?
Ans:Advantages of dry cell over simple cell are;

• Dry cell doesnot contain liquid so easy to handle.
• Dry cell is compact.
• Dry cell is cheaper than simple cell.

What is the role of MnO2 in dry cell?
Ans:MnO2 is depolarizer and in dry cell when hydrogen gas is collected in carbon rod then MnO2 reacts with it and does not give to accumulate at a place. This continues the flow of charges.
i.e. 2MnO2+ H2 --------- Mn2O3 + H2O


Define domestic circuit.
Ans: The alternating current circuit connected in houses, factories, industries, is called domestic circuit.


What are the precautions that should be followed during house wiring?
Ans: The precautions that should be followed during house wiring are:

•  The lines for lamps and power socket should be separated.
•  Switch and fuse should be used in circuits.
•  Proper fuse should be used in circuits.
•  Wire places and places attached with electrical appliances should be away from water leakage and dampness.

 

What is earthing?
Ans:The arrangement in domestic circuit that allows an unnecessary and leakage current to flow towards the ground with the help of suitable electrical wire is called earthing.


Why is earthing necessary?
Ans: Earthing is necessary in house wiring system because:

•  It prevents the electric leakage.
•  It saves the damage from lightening.
•  It reduces the loss of life and property by electric firing.

What type of combination of loads is used in house wiring system and why?
Ans: Parallel combination of loads is preferred in house wiring system because different switches can be made for different loads.


What do you mean by electrical devices? Write some examples of electrical devices.
Ans: The devices which convert electrical energy into other forms of energy are called electrical devices.
Examples of electrical devices are: electric lamp, electric heater, refrigerator, electric bell, telephone, computer, television, etc. 

What is the full form of CFL?
Ans: The full form of CFL is Compact Fluorescent Lamp.

What is electric lamp? Mention its types.
Ans: The electric device which converts electrical energy into light energy is called electric lamp. It is of two types. Filament lamp and fluorescent lamp.

What is electric bell?
Ans: The electronic device which converts electrical energy into sound energy with the help of temporary magnet is called electric bell.

What is fuse?
Ans: A thin piece of wire made up of an alloy of tin and lead used as safety device to prevent the overflow of current is called fuse.


What are the two characteristics of fuse?
Ans: The two characteristics of fuse are as follows;

• It has low melting point.
• It has high resistance.

How does fuse save the circuit?
Ans:When excessive current flows in the circuit, heat will be more. This heat causes to melt the fuse and circuit breaks. Thus further accident is saved from the fuse.

Write one disadvantage of fuse.
Ans:The main disadvantage of fuse is once it is melted we should replace the another wire.

Write the full form of MCB.
Ans:The full form of MCB is miniature circuit breaker.

What is MCB?
Ans:MCB is a developed form of fuse which automatically cuts off the main supply during overloading or short crcuit.


What is the advanctage of MCB over fuse?
Ans:The fuse should be replaced when it is melted but MCB cuts the circuit automatically and after switch on it starts its working.

Write any two difference between MCB and Fuse.
Ans:The following are the difference between MCB and Fuse:

MCB	Fuse
i) It switches off automatically during over loading or short circuiting.	i) It cuts off the circuit by melting itself.
ii) It is reset again by using flip-over switch.	ii) It should be replaced once it is melted.

 

What are the color codes of electric wires?
Ans:There are three electric wires in electric circuit.

• Phase wire or live wir ------- Reb/Brown
• Neutral wire ----------------- Blue/Black
• earthing wire ---------------- Green/Yellow

What is circuit? Draw a diagram to show it.
Ans:
The conducting path of the electricity where cell, wire,switch and load are connected is called electric circuit.

What are opne and close circuit?
Ans:Open circuit is a circuit in which current is not flowing or switch is off.
Close circuit is a circuit in which current is flowing or switch is on.

What do you mean by combination of cells? Name the types of combination of cells.
Ans:The process of arranging two or more than two cells in a circuit is called combination of cells.
There are mainly three types of combination of cells. They are:

• Parallel Combination
• Series Combination
• Mixed Combination

 

What is parallel combination of cells?
Ans:If the positive terminals of two or more cells are joined together at a point and all negative terminals are joined at another common point then the combination is called parallel combination of cells.

Write one advantage of parallel combination of cells.
Ans:The main advantage of parallel combination of cells is it works for long period of time.

Write one disadvantage of parallel combination of cells.
Ans:The main disadvantage of parallel combination of cells is that whatever be the increase in number of cells, the brightness of the bulb will not increase.

What is meant by series combination of cells.
Ans:If the positive terminal of first cell is connected to the negative terminal of second cell and positive terminal of second cell is connected to negative terminal of third cell and so on, then this type of combination is called series combination of cells.

What is the disadvantage of series connection of cells?
Ans:The main disadvantage of series connection of cells is it works for short time.

 

Distinguish between series and parallel combination of cells.
Ans:The difference between series and parallel combination of cells are:

Series Combination of cells	Parallel combination of cells
i) In series combination positive terminal of one cell is connected to negative terminal of other cell and son on.	i) In parallel combination all positive terminals of cells are connected and all negative terminals are connected at another point.
ii) Bulb glows with more brightness.	ii) Bulb glows with less brightness.
iii) Bulb glows for short time.	iii) Bulb glows for long time.