The understandable notes- ELECTRICITY CLASS-10

 ELECTRICITY AND ELECTRIC CURRENT

Electrcity is a form of energy that is used for various purposes. Electricity is used in nearly all places like in schools, hospitals, home, industries etc. 

When an electric charge flows through a conductor then we say that there is a current in conductor. 

Lets see how current is expressed 

The amount of charge flown through a particular area in  unit time is called electric current .

Rate of flow of charges is called current.

Now carefully see the symbols and equation 

I=Q/t      

Where I= current, Q= net charge , and t is time.

Also remember that this is average current not the instantaneous current beacuse instantaneous current use the delta which further requires oher mathematical operations like integration and differentiation etc. 

S.I unit of charge is coulomb 

S.I unit of current is ampere 

S.I unit of time is second

(Bijli ek prakar ki urja hai. Just kidding electricity urja yani energy ko hi kehte hai . Ab ye to sabhi ko pata hai ki energy kai forms me ho sakti hai, bas usi ka ek prakar bijli ya fir electricity hai. Ab bijli kaha kaha use hoti hai ye to batane ki jarorat nhi hai kyuji jis bulb or fan ko chalakar aap padh rahe ho vo bhi bijli se hi chal rahe hai. Ab yaha par ek chiz aati hai charge. Charge matter ki ek fundamental property hai jaisi ki mass. Jaise mass ko aap further nhi padh sakte vaise hi charge ko aap further nhi padh sakte. Ab current ki definition charge se hi aati hai. Rate ka matlab hota hai per unit time aur rate of flow of charges ka matlab hota hai ki kitni time mai kisi conductor se kitna charge flow hua. Bas isi ko current kehte hai. Ye baat yaad rakhna ki current tabbi banta hai jab charges flow hote hai. Agar charges flow nahi honge or ek jagah pr rhenge tb use current nhi bolenge tab vo static current ban jata hai.)

 Flow of charges generally means flow of electrons. In a wire the flow of electrons constitute electric charges. Now because charge is constituted by electrons and electrons have some mass, even their mass is considered is negligible, we can say that charge can not exist without mass. Means change in charge means change in mass. But when the phenomenon of electricity was discovered there is no concept of electrons so it is assumed that current flows from positive to negative but as electrons are negatively charged and flows towards positive side, current is divided in two types

Electronic charge- from negative to positive 

Conventional current- from positive to negative

Conventional current is generally opposite to the direction of flow of electrons and if not specifically mentioned, current means conventional current. 

(charges ke flow ko hi current bolte hai. Ab pichle saal aap ne structure of atom padha tha jisme aap sab ne ye padha ki electrons hi sirf atom ko leave kr sakte hai. Aur protons fixed hote hai. Vaise protons bhi kr sakte hai but vo nuclear reaction me aa jayega. To charges ke flow ka sidha sidha matlab ye hai ki electrons ka flow. Ab electron ka kuch mass bhi hota hai jisse ye pata chalta hai ki transfer of charge se kuch na kuch mass bhi transfer hota hai. Ab bahut purane time ki baat hai jab electrons ke bare me kisi ko pata nahi tha pr electricity discover ho chuki thi tab scientists ne ye anuman lagaya ki current positive se negative ki taraf flow hota hai. Bad mai jab electrons kai bare mai pata chala tab current ko do prakar me divide kr diya jisme ek electronic current aur dusra tha conventional current aur dono ki definition upar likhi hai. Ye sab basic hai isliye itni elonagted way me likh rha hu kyonki agar ye samajh nhi aaya to kuch samjh nhi aayega. ) 

An elctron possess a negative charge of 1.6*10^-19 coulomb. Also this is the smallest charge that can exist independently, means any charge will be a integral mutiple of this electronic charge. You can also calculate how much electronic charge or no of electrons are present in the given charge. For example in one coulomb of charge there are approximately 6*10^18 electrons are present.

Ampere unit is named after french scientist Andre Marie Ampere. 

Now from the equation we can say that flow of one coulomb of charge per second constitutes one ampere of current. Small quantities of current are expressed in milliampere

(1 mA = 10^–3 A) or in microampere (1 μA = 10^–6 A).

An instrument called ammeter measures electric current in a circuit. It is always connected in series in a circuit through which the current is to be measured. 

(Ek electron me jitna upar likha hai utna charge hota hai jo ki bahut kam hai pr itna hi hota hai. Aur ek electron me jo charge hota hai vo smallest charge hota hai jo exist kr ske yani ki koi bhi charge isse jo is se chota ho vo exist hi nhi kr paega. Aur chemistry me ye to padha hi hoga ki electron integral jaise ki 1, 2, 3 ki form hi tansfer hote hai. Yani aap kahi pr bhi 1/2 electron to transfer nhi kar sakte. Ab isse charge ki ek quantization ki property bhi aati hai pr vo higher classes ma hai. Abhi ki liye bas itna samajh lo ki kisi bhi conductor me jo total charge hoga vo is basic charge ka koi multiple hoga. Yani ki jab total charge ko electronic charge se divide karoge to ek integer aaega. Ab integer to sabko pata hi hoga jise nhi pata vo google pr dekh lo. Aur ampere ka naam kis scientist ke naam pr hai ye bhi likha hai book me vaise jaroori nhi hai pr yaad kr lena. Ab ampere jo hai vo current ki ek badi unit mani jati hai aur experiments ke time isse milliampere or microampere me represent krte hai. Mai aapko vaise exactly to likh kr nhi bata sakta lekin ^ symbol ka matlab raise to power yaad rakhna. Ab vo yantr jisse current to measure karte hai vo hai ammeter. Naam yaad rakhna aasan hai pr ye bhi yaad rakhna ki ise series me lagate hai. Series ka matlab to i think sabko pata hi hoga nhi pata to niche ka diagram dekh lo 

Isme ek hi wire me sabhi kuch jod diya jata hai. Ab jinhe ye bhi janna hai ki ammeter ko series mai hi kyo lagate hai vo thoda sabr rakhe kyonki jab potential ka concept aaega tab samjha dunga.)

ELECTRIC CIRCUIT 

A complete and closed path of electric current is called electric circuit. Circuits can be open or closed. In a open circuit the switch is off and current will not flow. In a closed circuit the switch is closed and current will flow. There are some basic components of circuit. A switch is able to make the circuit open or close. Wire is the path from which current flows. A resistor is a device which is used to give resistance or obstruction in the path of current. Ammeter is used to measure current and voltmeter is used to measure potential difference. A cell is a device that regulates the flow of electrons. Remember that battery or cell works  to maintain the flow of electron not supplying electrons. 

(Electric current ke closed path ko electric circuit bolte hai. Agar path closed na ho to current flow nahi hoga kisi bhi condition me. Ab switch band karke face ki taar pr hand mat rakhna nhi to body circuit complete kr degi aur aapko do yamdoot dikhai denge. Isliye aapne kai videos me dekha hoga ki kuch log shoes pahenkar current wire ko hath lagate hai kyoki unka contact earth se toot jata hai

 Ek baat yaad rakhna ki earth is also called as ocean of electrons, jo exessive charge hai earth use absorb kr leti hai. Baki kuch components hai unke bare me bhi likha hai padh lena aur niche ek ncert ka diagram laga rha hu ise dhyan se padh kar yaad kr lena kyonki iske bina diagram samajh nhi aayega. )