THE UNDERSTANDABLE NOTES , ELECTRIC CHARGES AND FIELDS, CLASS 12, PART -1
THE UNDERSTANDABLE NOTES
ELECTRIC CHARGES AND FIELDS - PART 1
[FOR SESSION -: 2023-24 ]
SYLLABUS- Electric charges, Conservation of charge, Coulomb's law-force between two- point charges, forces between multiple charges; superposition principle and continuous charge distribution. Electric field, electric field due to a point charge, electric field lines, electric dipole, electric field due to a dipole, torque on a dipole in uniform electric field. Electric flux, statement of Gauss's theorem and its applications to find field due to infinitely long straight wire, uniformly charged infinite plane sheet and uniformly charged thin spherical shell (field inside and outside).
NOTE- These notes are made by deeply analyzing NCERT, referance books, online lectures so must be enough for boards.
INDEX- Translation is inside curly brackets ().
The branch of physics that deals with the study of charges at rest is called electrostatics.
(physics ki vo shakha jo ki charge ke rest ya fir sthir hone pr hame padhne ko majbur kre use electrostatics kehte hai.)
Some daily experiences of static current are-
(Ye to samjhane ki jarorat nhi hai na)
- When a glass rod is rubbed with silk cloth, the rod began to attract pieces of paper.
- When a comb is combed in dry hair, it also gets electrically charged and began to attract piece of paper
- When two balloons are rubbed with silk cloth, they began to repel each other.
- Trucks and tankers have a chain dragging on the road. This is because static charges are developed due to air drag. Because of this, a tiny spark will create and turn into a disaster if the container contains any flammable material.
ELECTRIC CHARGES
Charge is something possessed by materialistic objects which makes it possible for them to exert electrical force and to respond them to electrical force. Charge is intrinsic property of matter on which electrical force is dependent.
(charge kisi matter ki vo property hai jis pr electrical force depend krta ho. Intrinsic ka matlab tum thik thik ye lagalo ki vo property jise aur depply na padh sake jaise maas vagera)
Charges are basically of two types - Positive and Negative. The property which differentiates the two kin of charges is called Polarity of Charges. Two charges of same polarity repel each other while two charges of different polarity attract each other.
(ye to pata hi hoga ki same charges ek dusre ko repel krte hai aur opposite charges ek dusre ko attract krte hai. )
The vast amount of charge inside an object is usually hidden because each object contains equal number of protons and electrons. This conditions is called as balanced charge or neutral object. thus we can say that an object is neutral when it contain equal amount of positive and negative charge.
(dekho har ek object ke andar same number ke electron aur proton hote hai aur dono pr charge bhi same magnitude ka hota hai, is wajah se koi bhi object electrically neutral hota hai jab tak usme kuch khurafat na kar di jaye, khurafat se mera matlab hai ki jab usme se kisi ek charge ko nikal lena ya fir kisi ek charge ko aur andar daal dena. ise aise samjho ki kisi object ko mai do tariko se negative charge kr skta hu, ek to usme se positive charge nikal kr aur dusra usme aur negative charge daal kr.)
To charge an object, we always need to excess or deficit one kind of charge.
(jo uper samjhaya hai vahi hai.)
The cause of charging is actual transfer of electron. Electrons are transferred from material whose lower to material whose work function to higher work function.
(kisi bhi object ko charge hone ka reason transfer of electron hai. Proton nhi hai. Electrons hamesha lower work function se higher work function pr transfer hote hai. Ab jin mahan bacho ko work function hi nhi pta to work function is defined as minimum energy reqiured to eject electron from a material. matlab kisi material me se electron nikalne ke liye kitni energy required hai.)
The charge transferred by rubbing is a very small fraction of total charge. Charge on insulated bodies like Glass, plastic are static and does not get spread all over. A negatively charged body slightly gains weight and a positively charge body slightly reduces weight.
(jo charge rubbing ke through transfer hota hai vo total charge ke comparison me bahut kam hota hai. aur insulators pr charge ek jagah jama rehta hai. agar charge jama na rahe to jo comb paper ko attract krta hai vo nhi krega kyoki vo charge hamari body se earth me transfer ho jayega.ab negatively charge hone ka matlab hai ki kuch electrons ko gain krna. electrons ka mass vaise to neglible hota hai pr hota to hai na. isliye negatively charged body weight ko increase krti hai aur positively charged body weight reduce krti hai.)
EARTHING
It is the process of transfer of any excess charge to earth. Earth is defined as ocean of electrons.
(vaise to ye topic cut hai pr samaj lo. earth me koi sa bhi charge chahe fir vo postive ho ya negative ho agar excess me hai to discharge ho jayega. iske liye tum ghar me earhing ka process padh lena. Syllabus me nhi hai to mai kyo time waste kru.)
QUANTIZATION OF CHARGE
The smallest charge that can exist independently is charge on electron.
The total charge on any body is an integral multiple of the electronic charge.
ELECTRONIC CHARGE =1.6 * 10^-19 Coulomb
or Total charge Q= ne
where Q= total charge
n= integer
e= electronic charge
Quantization of charge has no practical value because electronic charge is very small and to gain or reduce charges in terms of 'e' is not visible. So, the grainy nature of charges is lost and it appears to be continuous.
(dekho kisi bhi body pr jo total charge hoga vo is basic charge yani ki charge on electron ya charge on proton ka ek integral multiple hoga. Integer to pata ho hoga nhi pata to pehle 9th class padho. iska matlab ye hai ki kabhi bhi half electronic charge nhi milega. is se ham ye pata laga sakte hai ki koi charge exist krta bhi hai ya nahi. Agar in notes pr tumhara response acha raha to iski exercise bhi bana dunga. Or jisko ab bhi samajh nhi aaya to vo bas itna samajh lo ki agar tum stairs pr khade ho to tum ya to ek step upar jaoge ya fir ek step niche. Ramp wala kaam nhi hai.)
CONSERVATION OF CHARGE
It is the property by virtue of which the total charge inside an isolated system remains constant. Charge can be created in equal and unlike pairs only.
(kisi bhi isolated system yani ki vo system jisme external influence zero ho usme total charge conserve rehta hai.)
DIFFERENCE B/W CHARGE AND MASS
|
CHARGE |
MASS |
|
1.
Charge is that property of matter on which electric
force depends. 2.
Charge can be positive or negative or zero. 3.
Charge is independent of speed. 4. Charge is quantized. 5.
Charge is conserved. 6.
Force between two charge can be attractive or
repulsive. 7.
An accelerated charge emits radiation. 8.
Charge cannot exist without mass. 9.
Charge is a derived unit. |
1.
Mass is that property of matter on which
gravitational force depends. 2.
Mass is always positive. 3.
Mass of a body increases with increase in speed. 4.
Quantization of mass has not yet been established. 5.
Mass is not conserved as it can be changed into
energy and vice versa. 6.
Force between two masses is always attractive. 7.
Accelerated mass emits no radiation. 8.
Mass can exist without charge. 9.
Mass is a fundamental unit. |
m= mass ob body
mo= rest mass
v= velocity of body
v= velocity of body
c= speed of light
is equation ke hisab sai jaise jaise speed of body increase hogi vaise hi mass bhi increase hoga aur jab speed of body speed of light ke equal hogi tab mass infinite ho jyaega. isi wajah se keval photons hi light ki speed se travel kr pate hai. Aur charge ka matlab electrons se hi hota hai kyoki protons to move nhi krte. vaise to electrons ka mass neglible hota hai pr hota to hai na. isi liye charge cannot exist without mass.)
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