Static Electricity - Weebly
Transcript of Static Electricity - Weebly
Introduction
• ‘elektron’ ( Greek )
– amber (hard translucent resin)
• Thales
– rubbed amber with fur/wool
• William Gilbert
– Glass, sealing wax, plastic, nylon
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• Electrics (substances) – Acquires attractive property
• Electrified or charged (rubbed bodies)
• Static Electricity– Charge not allowed to flow
• Electrostatics– Branch of electricity
– Study of properties of bodies electrified due to stationary charge
Introduction
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• Glass
• Plastic
• Ebonite
• Amber
• Nylon
• Hard rubber
Charging by Friction
• Wool
• Fur
• Silk
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• Positive
• Negative
Types of Charges
Rubbing of two different non-
conducting objects – movement of
electronsChris Sanandam
1. Skin of cat2. Fur3. Glass4. Cotton5. Silk6. Wood7. Indian rubber8. Resin9. Amber10.Sulphur11.Ebonite
Objects
Glass rubbed with fur
Glass rubbed with silk
+-
+ -
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• Electrically neutral (normal state)
– Protons (+e)
– Electrons (-e)
– Neutrons (no charge)
• Mass of proton = mass of neutrons = mass of a hydrogen atom
• Mass of electron = mass of proton
Atom
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• No. of protons & neutrons are different for different elements
• Protons & neutrons are held by nuclear force
• Normal state
Atom
Hydrogen Helium Lithium
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• Valence electron– Outermost orbit
– Attractive force gets weaker as the distance from nucleus increases
• Free electron – When a solid is formed electrons in outermost
orbit leave their atoms
– Move around freely in the solid
Atom
Bound electrons
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Transfer of electrons• Case 1:
– Duster & polythene electrically neutral
– When both are rubbed
– Duster (loses electron) becomes +ve
– Polythene (gains electron) becomes –ve
• Case 2– Duster & cellulose acetate electrically neutral
– When both are rubbed
– Cellulose acetate (loses electron) becomes +ve
– Duster (gains electron) becomes –ve
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Electrostatic Induction
Conservation of ChargeCharge is neither created nor destroyed, but transferred from one body to another Chris Sanandam
Static Electricity
• Electrostatic Induction
– Process
– Opposite charge is induced on the nearer end
– Similar charge is induced on the farther end of an uncharged conductor
• Note: induction occurs readily in conductors & is poor in insulators
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Electroscope
• Device
• Detect the presence of charge
• Identify the nature of charge
Types• Pith ball electroscope
• Gold leaf electroscope
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Gold Leaf Electroscope
Brass Disc (cap)
Insulator plug
Brass Rod (stem)
Gold leaves
Glass bottle
Earth
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Sparking
• The flow of charge
• Between two charged bodies
• Brought close to each other
• With spark & chit-chit sound
• Due to ionisation of air
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