Class 12th Physics-Electric Charges and Fields- Fundamental Concepts of electric Charge -part-2

Class 12th Physics-Electric Charges and Fields- Fundamental Concepts of electric Charge -part-2

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Sure! Here’s a Class 12 Physics explanation of the chapter “Electric Charges and Fields”, focusing on:

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Chapter: Electric Charges and Fields

Topic: Fundamental Concepts of Electric Charge – Part 2

Class: 12th CBSE/NCERT

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Quick Recap from Part 1:

• Electric charge is a basic property of matter.

• It can be positive (like proton) or negative (like electron).

• Like charges repel, unlike charges attract.

• Charge is quantized and conserved.

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Part 2: Fundamental Concepts Continued

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1. Quantization of Charge

• Charge exists in discrete packets, not continuous.

• Smallest unit of charge = charge of an electron
  e=1.6×10−19 Coulombse = 1.6 \times 10^{-19} \, \text{Coulombs}e=1.6×10−19Coulombs

Formula:
Any charge $q=\pm n\cdot e$
Where:

• $n$ = any integer (1, 2, 3, …)

• $e$ = elementary charge

Example:
If a body has charge q=3.2×10−19 Cq = 3.2 \times 10^{-19} \, Cq=3.2×10−19C, then:
$n=q/e=2$ → It has 2 extra electrons

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2. Conservation of Charge

• Charge can neither be created nor destroyed, only transferred.

• Total charge before and after any physical process remains constant.

Example:
In rubbing a glass rod with silk:

• Glass loses electrons → becomes positively charged

• Silk gains electrons → becomes negatively charged

• Net charge = 0 (balanced)

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3. Additivity of Charge

• Charges are scalars (they add algebraically).

• Total charge = Sum of individual charges

Example:
If a body has +3 C and -2 C on different parts,
Net charge = $3C-2C=+1C$

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4. Methods of Charging

1. Friction:

   • By rubbing two objects (e.g., balloon on hair)

   • Transfers electrons

2. Conduction (Contact):

   • Charged object touches a neutral object

   • Charge gets shared

3. Induction:

   • No contact needed

   • A charged object brought near induces opposite charge in a conductor

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Real-Life Application:

• Electrostatic dust precipitators use electric charge to clean factory smoke.

• Photocopiers and laser printers work using charge principles.

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Summary (Key Points):

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Class 12th Physics-Electric Charges and Fields- Fundamental Concepts of electric Charge -part-2

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