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# Capacitors Assignment Help

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Electromagnetism - Capacitors

A device to store charge or electrostatic energy is called a capacitor.

Capacitance it is the capacity of a capacitor to store charge. In a capacitor **Q ∝ V or Q = CV; C** is called the capacitance

**C = (M**_{1} L^{-2} T_{4} A^{2})

According to shapes, capacitors may be of three types: spherical parallel plate and cylindrical.

Unit of capacitance is faraday **1F (IC/IV)**

IF is a very big unit, Therefore, **µF or nF or µµ F (pF)** and so on are used.

Spherical capacitors may be of two types

Isolated spherical capacitor

Concentric spherical capacitor

Isolated spherical capacitor is a single sphere. Its capacitance is given by **C = 4πε**_{0}R where R is radius of the sphere.

Two concentric spherical shells or the inner one may be solid.

**C = 4πε**_{0} (R_{2} R_{1}) / (R_{2} - R_{1})

If a dielectric of strength K is introduced between **R**_{1} and **R**_{2}

**C = 4πε**_{0} k R_{2} R_{1 }/ R_{2 }- R_{1}

**Parallel plate capacitor **

If A is area of each plate and d is the separation between two plates then

**C = ε**_{0} (A/d) with free space as dielectric

**C = Kε**_{0} (A/d) if a dielectric of strength k is added

If the dielectric slab has thickness **t (t < d)** then

If a dielectric of strength k is introduced in between electrolytic capacitors may have high values and go upto mF.

Capacitance of a cylindrical capacitor

**C = 2πε**_{0}l / log e r_{2} / r_{1}

If the space between two cylinders is filled with a dielectric of strength k then

**C = 2πε**_{0}kl/r^{2}

Log **e r**_{1}

Magnitude of induced charge **Qp = Q [1 - /1 / k]**

Force between the plates of a capacitor (attractive force)

**F = (Q**^{2}/2) A ε_{0}

Energy stored (electrostatic) in a capacitor

**U = (1/2) CV**^{2} = Q^{2}/2C = QV/2

Energy stored per unit volume =** [(1/2) ε**_{0}E^{2}]

Where E is electric field intensity. The capacitance of a variable tuning capacitor (used for tuning radio) having n plates is

**C = (n - 1)A ε**_{0}/d where d is the separation between each plate.

If dielectrics are added in the manner shown, then the net capacitance from equivalent circuit is a parallel combination of **C**_{1}, C_{2} and C_{3} Hence

**C**_{1} = ε_{0} K_{1} [(A/3)/d] C^{2} = ε_{0} K^{2} [(A/3)/d] C^{3} = ε_{0} K^{3} [(A/3)/d]

If the dielectrics are arranged as shown in ten from equivalent circuit it is evident that the net capacitance is a series combination of **C**_{1}, C_{2} and C_{3}

ExpertsMind.com - Capacitors Assignment Help, Capacitors Homework Help, Capacitors Assignment Tutors, Capacitors Solutions, Capacitors Answers, Electromagnetism Assignment Tutors

Capacitance it is the capacity of a capacitor to store charge. In a capacitor

**Q ∝ V or Q = CV; C**is called the capacitance

**C = (M**

_{1}L^{-2}T_{4}A^{2})According to shapes, capacitors may be of three types: spherical parallel plate and cylindrical.

Unit of capacitance is faraday

**1F (IC/IV)**

IF is a very big unit, Therefore,

**µF or nF or µµ F (pF)**and so on are used.

Spherical capacitors may be of two types

Isolated spherical capacitor

Concentric spherical capacitor

Isolated spherical capacitor is a single sphere. Its capacitance is given by

**C = 4πε**where R is radius of the sphere.

_{0}RTwo concentric spherical shells or the inner one may be solid.

**C = 4πε**

_{0}(R_{2}R_{1}) / (R_{2}- R_{1})If a dielectric of strength K is introduced between

**R**

_{1}and

**R**

_{2}

**C = 4πε**

_{0}k R_{2}R_{1 }/ R_{2 }- R_{1}**Parallel plate capacitor**

If A is area of each plate and d is the separation between two plates then

**C = ε**with free space as dielectric

_{0}(A/d)**C = Kε**if a dielectric of strength k is added

_{0}(A/d)If the dielectric slab has thickness

**t (t < d)**then

If a dielectric of strength k is introduced in between electrolytic capacitors may have high values and go upto mF.

Capacitance of a cylindrical capacitor

**C = 2πε**

_{0}l / log e r_{2}/ r_{1}

If the space between two cylinders is filled with a dielectric of strength k then

**C = 2πε**

_{0}kl/r^{2}

Log

**e r**

_{1}

Magnitude of induced charge

**Qp = Q [1 - /1 / k]**

Force between the plates of a capacitor (attractive force)

**F = (Q**

^{2}/2) A ε_{0}

Energy stored (electrostatic) in a capacitor

**U = (1/2) CV**

^{2}= Q^{2}/2C = QV/2Energy stored per unit volume =

**[(1/2) ε**

_{0}E^{2}]Where E is electric field intensity. The capacitance of a variable tuning capacitor (used for tuning radio) having n plates is

**C = (n - 1)A ε**where d is the separation between each plate.

_{0}/dIf dielectrics are added in the manner shown, then the net capacitance from equivalent circuit is a parallel combination of

**C**

_{1}, C_{2}and C_{3}Hence

**C**

_{1}= ε_{0}K_{1}[(A/3)/d] C^{2}= ε_{0}K^{2}[(A/3)/d] C^{3}= ε_{0}K^{3}[(A/3)/d]If the dielectrics are arranged as shown in ten from equivalent circuit it is evident that the net capacitance is a series combination of

**C**

_{1}, C_{2}and C_{3}

ExpertsMind.com - Capacitors Assignment Help, Capacitors Homework Help, Capacitors Assignment Tutors, Capacitors Solutions, Capacitors Answers, Electromagnetism Assignment Tutors