12.4-Transfer of Charge

12.4-Transfer of Charge Important Formulae

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12.4-Transfer of Charge
  • Charge transfer occurs when electric charge moves from one object to another.
  • This can happen by conduction, induction, or friction.
  • When two objects come into contact, charge may flow between them, depending on their electric potential.
  • In the process of conduction, electrons move from a negatively charged object to a positively charged one.
  • Formula for electric force: $F = \dfrac{k q_1 q_2}{r^2}$, where $q_1$ and $q_2$ are the charges, $r$ is the distance between them, and $k$ is Coulomb's constant.
  • Charging by friction occurs when two objects are rubbed together, transferring electrons from one object to another.

12.4 - Transfer of Charge

The transfer of charge is a key concept in understanding electrical phenomena. When two bodies interact, charge can be transferred from one body to another. This phenomenon is commonly observed when objects like balloons, combs, or rubbers are rubbed against other materials. The transfer of charge can happen through several processes: conduction, induction, and friction.

Conduction

Conduction is the process where charge is transferred through direct contact between materials. It occurs when two objects with different charges are brought in contact. Electrons move from the object with higher negative charge to the one with lower negative charge (or the more positive object), leading to a redistribution of charges. This process typically occurs in conductors, such as metals, where electrons are free to move.

Example: When a negatively charged metal rod touches a neutral metallic sphere, the negative charges are transferred from the rod to the sphere. As a result, both the rod and the sphere acquire the same type of charge, which is negative in this case.

Induction

Induction refers to the process by which a charged object can induce a charge in another nearby object without direct contact. In this case, the electric field of a charged body influences the charge distribution in the nearby neutral object. Although no actual transfer of electrons occurs, a separation of charges (polarization) happens in the nearby object.

Example: If a negatively charged rod is brought near a neutral metal sphere, the electrons in the sphere will be repelled, creating a positive charge on the side near the rod and a negative charge on the far side. If the sphere is grounded, the negative charges can flow away, leaving the sphere with a net positive charge.

Friction

Friction is one of the most common methods of charge transfer. When two objects are rubbed together, electrons are transferred from one material to the other. The material that gains electrons becomes negatively charged, while the material that loses electrons becomes positively charged. This process is most visible with materials like rubber and wool or plastic and fur.

Example: When a rubber rod is rubbed with fur, electrons from the fur transfer to the rubber rod, making the rod negatively charged and the fur positively charged.

Quantifying Charge Transfer

The amount of charge transferred during these processes can be expressed in terms of the charge quantity. The basic unit of charge is the Coulomb (C). The formula for calculating the charge is:

Formula: $Q = It$

Where:

  • $Q$ = Charge (in Coulombs, C)
  • $I$ = Current (in Amperes, A)
  • $t$ = Time (in seconds, s)

In practical terms, the transfer of charge depends on factors like the material properties, the amount of contact, and the nature of the charges involved. Conductors allow for easier charge transfer, while insulators hinder it.

Electrostatic Induction

Electrostatic induction is the process where a neutral object is charged by the influence of a nearby charged object, without direct contact. For example, when a charged rod is placed near a metal object, it causes the free electrons in the metal to move, resulting in one side of the metal becoming negatively charged and the other side positively charged.

Example: If a negatively charged rod is brought near a neutral metal sphere, the electrons in the sphere are repelled by the rod. If the sphere is then grounded, electrons from the ground will flow into the sphere to neutralize the positive charge on the side near the rod. Once the ground connection is removed, the sphere will have a net negative charge.

Key Points:
  • Charge can be transferred through conduction, induction, and friction.
  • Conduction involves direct contact between materials, allowing electrons to move.
  • Induction involves the influence of a nearby charged object without contact, leading to a redistribution of charges.
  • Friction occurs when two objects are rubbed together, causing a transfer of electrons.
  • The amount of charge transferred is measured in Coulombs (C).

12.4 - आवेश का स्थानांतरण

कक्षा 8 विज्ञान के अध्याय "कुछ प्राकृतिक परिघटनाएँ" में आवेश का स्थानांतरण एक महत्वपूर्ण विषय है। इस अनुभाग में, हम समझते हैं कि आवेश का स्थानांतरण कैसे होता है और इसके पीछे के सिद्धांत।

आवेश क्या है?

आवेश एक भौतिक गुण है जो किसी वस्तु पर धनात्मक या ऋणात्मक रूप में हो सकता है। वस्तुओं पर स्थिर आवेश विद्युत स्थिरता का आधार बनता है।

आवेश का स्थानांतरण

आवेश का स्थानांतरण तीन मुख्य तरीकों से हो सकता है:

  • घर्षण (Friction): जब दो वस्तुएं एक-दूसरे के संपर्क में आती हैं और फिर अलग होती हैं, तो आवेश का स्थानांतरण होता है। उदाहरण के लिए, जब रेशम के कपड़े को कांच की छड़ी से रगड़ा जाता है, तो कांच धनात्मक आवेशित हो जाता है और रेशम ऋणात्मक।
  • स्पर्श (Conduction): जब एक आवेशित वस्तु किसी अनावेशित वस्तु को स्पर्श करती है, तो आवेश का स्थानांतरण होता है। इस प्रक्रिया में, आवेशित वस्तु अपने आवेश का कुछ भाग अनावेशित वस्तु को दे देती है।
  • प्रेरण (Induction): इस प्रक्रिया में, बिना किसी भौतिक संपर्क के, आवेश का स्थानांतरण होता है। जब एक आवेशित वस्तु किसी अन्य वस्तु के पास लाई जाती है, तो दूसरी वस्तु पर आवेश उत्पन्न हो सकता है।
आवेश संरक्षण का नियम

आवेश संरक्षण का नियम कहता है कि आवेश न तो उत्पन्न किया जा सकता है और न ही नष्ट किया जा सकता है। इसे निम्नलिखित प्रकार से व्यक्त किया जा सकता है:

$q_{\text{total}} = q_1 + q_2 + \ldots + q_n = \text{constant}$

आवेश स्थानांतरण का महत्व

आवेश स्थानांतरण का उपयोग विभिन्न तकनीकी और वैज्ञानिक उपकरणों में होता है। जैसे:

  • वायुमंडलीय बिजली का अध्ययन
  • विद्युत स्थैतिक पेंटिंग
  • फोटोकॉपी मशीन
विद्युत धारा और आवेश

जब आवेश एक चालक के माध्यम से प्रवाहित होता है, तो इसे विद्युत धारा कहा जाता है। विद्युत धारा का गणितीय रूप में परिभाषा इस प्रकार है:

$I = \frac{q}{t}$

जहां,

  • $I$ = विद्युत धारा (ampere)
  • $q$ = कुल आवेश (coulomb)
  • $t$ = समय (second)