current | resistivity | Current electricity | ohm law | electric current | physics

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Current electricity and ohm's law(Current electricity) :- •What is current? Rate of flow of electric charge with time through any cross section of a wire is called current. It is denoted by I . Thus if charge "dq" flows through a wire in small time "dt" then electric current through wire is given by :                                             I=dq/dt  1 ampere = 1coulomb/1 second  1A=C/s •Ampere :-                                                           The current Through a wire is called one ampere if one coulomb charge is flow through Any cross section of wire in one second   •Ohm's law:- Ohm’s principal discovery was that the amount of electric current through a metal conductor...
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Conductors,insulators and dielectrics |electostatic | physics

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Conductors, insulators and Dielectrics  (Electrostatic)  


• What is conductor ?

Conductors are the Materials or substances which allow electricity to flow through them. They conduct electricity because they allow electrons to flow easily inside them from atom to atom. Also, conductors allow the transmission of heat or light from one source to another.
Metals,humans, earth,  and animals are all conductors. This is the reason we get electric shocks! Moreover, the human body is a good conductor. So it provides a resistance-free path for the current to flow from wire to body.
Conductors have free electrons on its surface which allow current to pass through easily. This is the reason why conductors are able to conduct electricity .

Example :-

• Material such as silver is the best conductor of electricity. But, it is costly and so, we don’t use silver in industries and transmission of electricity.
• Copper, Brass, Steel, Gold, and Aluminium are good conductors of electricity. We use them in electric circuits and systems in the form of wires.
• Mercury is an excellent liquid conductor. Thus, this material finds use in many instruments.


• What is insulator? 

Insulators are materials that hinder the free flow of electrons from one particle of the element to another. If we transfer some amount of charge to such an element at any point, the charge remains at the initial location and does not get distributed across the surface. The common process of charging of such elements includes charging by rubbing and charging by induction

Example :-

• Glass 
• wood
• Rubber 
• plastic
• Air


• What is dielectrics?

The insulators, on faces of which induced charge are take place when these are placed in an electric field are called dielectrics

Example :-

• Mica
• Plastics 
• Glass 
• Porcelain
• various Metal oxides


• Some important board exam level question answers :- 


Q. 1) what are dielectrics  ? Give some examples. 

Ans:-  The insulators, on faces of which induced charge are take place when these are placed in an electric field are called dielectrics
Example :-
Mica, Plastics , Glass ,Porcelainvarious Metal oxides.

Q. 2)  Give the name of five Materials  which are conduct electricity ?

Ans:- Silver,  Copper, iron, Steel, aluminum etc. 

Q. 3) Give the name of five materials which do not conduct electricity  ?

Ans:- Wood, Glass, rubber, plastic, air. 








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Physics

Electric lines of force (electrostatic) | electostatic | physics

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 •  Electric lines of force        (Electrostatics)  1. The electric lines of force start from positive charge and end at negative charge.      2.  The lines of forces originate or terminate at a surface is always right angle to that surface. 3. The lines of forces never intersect each other. 4. The electric lines of force do not pass through a conductor. 5.Like charges repel each other wherever unlike charges attracted each other  • Some important Question Answer From Board level Exams:- Q. 1) Why electric field lines of force cannot intersect each other?   Ans:- This is because at the point of intersection, two tangent would have to be drawn to the lines of Force. Therefore would be two directions of electric intensity at the same point, which is not possible.  Q. 2) Write Two properties of electric field lines of force?  Ans:-    1. The lines of forces ...
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current | resistivity | Current electricity | ohm law | electric current | physics

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Image
Current electricity and ohm's law(Current electricity) :- •What is current? Rate of flow of electric charge with time through any cross section of a wire is called current. It is denoted by I . Thus if charge "dq" flows through a wire in small time "dt" then electric current through wire is given by :                                             I=dq/dt  1 ampere = 1coulomb/1 second  1A=C/s •Ampere :-                                                           The current Through a wire is called one ampere if one coulomb charge is flow through Any cross section of wire in one second   •Ohm's law:- Ohm’s principal discovery was that the amount of electric current through a metal conductor...
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Electric field (electrostatic) | electostatic | physics

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Electric field (Electrostatics)  . The space around a charge in which any other charge is acted upon by an electrostatic force is called electric field of charge .                   E = F/q.                  We know that,           F = k Qq. / r 2            Therefore                 E = k Qq. / r 2 *1/q.                      E =kQ/ r 2   The charge "Q" due to which electric field is set up is called source charge and the other charge "q." which experience electrostatic force in the electric field is called test charge . Electric field intensity :- The electric field intensity or electric field strength at a point due to a source charge may be defined as the electrostatic force per unit positive charge a...
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State and prove the Gauss's Theorem (electrostatic) | electostatic | physics

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Gauss’s Theorem (Electrostatic)   Statement:- According to Gauss’s theorem the net-outward normal electric flux through any closed surface of any shape is equivalent to 1/ε0 times the total amount of charge contained within that surface. Proof of Gauss’s Theorem Statement:- Let the charge be = q Let us construct the Gaussian sphere of radius = r Now, Consider , A surface or area ds having ds (vector) Normal having the flux at ds: d e = E (vector) d s (vector) cos θ But , θ = 0 Therefore, Total flux: C = f d Φ E 4 π r2 Therefore, σ = 1 / 4πɛo q / r2 × 4π r2 σ = q / ɛo • Some important board exam level question answers:- Q. 1) Write Gauss's theorem for a charge outside a closed surface.  Ans:- The theorem becomes zero.  Q. 2) What is an equipotential surface ? Ans:- A surface, which has same electric   potential everywhere on it is called   equipotential surface.  Ask me qu...
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