EC STUDY

Van de Graaff Generator     It is an arrangement established by Van De Graaff to building up high potential difference of order 10^7 volts. It works on the following two principles The charges given to the sphere spread to the outer surface of the conductor                  if two concentric spherical conductors are connected by a wire, the charges will flow from the inner conductor to outer conductor, whatever be the potential of the conductor.     2. Discharging action of sharp points ( Corona Discharge )          The surface charge density of a conductor is  σ =Q/A.   which means the charge density is more in small or sharp region.  Construction Of Van de Graaff Generator It consisted of a large hollow metallic sphere mounted on two insulated supporting columns. An endless belt of an  insulating material (Nylon) is mounted on pulleys P1 & P2 which is run by a motor. ...

Energy Stored In A Capacitor     We have already studied that capacitors store electrostatic energy in it. Today we will learn how they store energy? and how much energy can be store in a capacitor? As always to find the energy we have to find the work done. So, consider a small positive charge +dQ, work has to be done to transfer this small +dQ to move towards this positive plate(because it's against the electric field). This work is stored as potential energy. Work done W = charge X potential i.e, W =qV Here charge is dQ so we can write dW = dQ V = dQ Q/C               ( from equation Q = CV ) integrating on both sides we get  This equation consisted to be general equation. By substituting values of Q and C we get other 2 forms of energy stored in capacitor    applying Q = CV in equation (1) applying C = Q/V in equation (1)     Prev      Next You may be Interested In  Physics Previous Questi...

Effect Of Dielectric On A Capacitor     If the dielectric introduces in between the plates, the dielectric get polarized by the electric field. So we have to consider the surface charge densities of dielectric  +  p  and  -   p   Conclusion           We can increase the capacitance of a parallel plate capacitor by introducing dielectric in between the plates. Here K is the dielectric constant, which should be greater than 1.       Prev      Next Previous year question paper with answer key   Browse more topics under Electrostatic Potential & Capacitance Electrostatic Potential, Potential Energy, Potential Energy Difference Potential Due To A Point Charge Potential Due To An Electric Dipole Equipotential Surface & Its Properties Potential Energy In An External Electric Field Potential Energy Due To A Single Charge In An External Electric Field Potential Energy Due To A Syst...

Parallel Plate Capacitor Parallel Plate Capacitor      A parallel plate capacitor consisted of two large conducting plates separated by a small distance. When the battery is connected across the battery, the plates get charged and establish an electric field. The electric field inside the capacitor has a direction from the positive plate to the negative plate.  The capacitance of Parallel Plate Capacitor Without Dielectric  Consider a parallel plate capacitor  of two large conducting plates separated by a small distance d. The area of each plate is A. The distance d is much smaller than area A. so we can write A>>d.  To find the capacitance there are 3 steps to follow, first we want to find the electric field E , then the potential V and finally capacitance C using equation C=Q/V  E → V →C=   Q/V For finding the total electric field divided the entire area into 3, region 1, region 2 & region 3 like this. Electric field in region 1, ...

#9. Capacitor And Capacitance  What is a Capacitor? The capacitor is the device that is used to store electrical energy. It consisted of two electrical conductors separated by a distance. The space between the conductors may be filled with an insulating material known as dielectric. The ability of capacitor to store charge is known as capacitance . This is the symbolic representation of the capacitor Working Of The Capacitor Before explaining the working of a capacitor, let's consider this basic circuit diagram of parallel plate capacitor. There are two conductors plates separated by a small distance 'd'. The space between the conductors is filled with dielectric.  The working of the capacitor can be divided into two parts (1) charging of the capacitor (2) discharging of the capacitor Charging of the capacitor When we connect the DC supply to the capacitor, one plate is connected to the positive plate and the other plate is connected to the negative plate. When the potentia...

#8. Dielectric And Polarization What are dielectrics? Dielectrics are non-conducting substances or insulators. Dielectrics can be easily polarized when an electric field is applied to it. Thus their behavior in an electric field is entirely different from that of conductors.  Electric Field Inside A Dielectric  Consider a plate of conductor a positively charged one & another plate of a conductor which is negatively charged. So, in between them there exist electric field Eout from positive plate to negative plate. Now we are going to place a dielectric inside this electric field. under the influence of this electric field, the dielectric get polarised (polarisation means giving direction). Inside the dielectric there exist positively charged protons and negatively charged electrons.  The positively charged protons will move towards the negative plate and negatively charged electrons move towards the positive plate. As the result of this alignment of charges, an interna...

#7. Electrostatics Of Conductors Now we are going to discuss the behavior of the conductor  1. Inside the conductor, the electrostatic field is zero We are going to discuss the behavior of the conductor when it is placed in the electric field. So for that, we have to create the electric field.  Consider a plate of conductor which is positively charged one & another plate of a conductor which is negatively charged. So, in between them there exist electric field Eout from positive plate to negative plate. Now we are going to place a conductor inside this electric field. Inside the conductor, there are negatively charged electrons and positively charged protons. The positively charged protons will move towards the negative plate and negatively charged electrons move toward the positive plate. As the result of this alignment of charges an internal electric field Ein gets produced, which direction is exactly opposite to Eout and magnitude is the same. Hence Eout and Ein ge...

#3. Electrostatic Potential Due To An Electric Dipole We already know that electric dipole is an arrangement which consists of two equal and opposite charges +q and -q separated by a small distance 2a. Electric dipole moment is represented by a vector  p  of magnitude 2qa and this vector points in direction from -q to +q. To find electric potential at point P due to a dipole consider charge -q and charge +q separated by a distance 2a.  r 1  and r 2  respectively are distance of charge +q and -q from point P. Since electric potential obeys superposition principle so the net potential due to electric dipole as a whole would be sum of potential due to both the charges +q and -q. Thus Special Cases Potential at a point on the axial line i.e  θ = 0 Potential at a point on the equatorial line  i.e  θ = 0   You may interested in  Previous Year Question Paper With Answer Key Browse more topics under Electrostatic Potential & Capacitance Elec...

#6. Potential Energy Of A Dipole In An External Electric Field Consider a dipole placed in a uniform electric field at an angle ‘ θ ’ with the electric field. The torque experience by the dipole is  Torque ( τ ) = Force x perpendicular distance Here the perpendicular distance is BC. From the triangle ABC we can find the distance BC sin⁡ θ =  BC/2l i.e, BC=  2 l sin θ  by applying value of BC we get  Torque ( τ ) =  Force x 2 l sin θ                      =  q E 2 l sin θ                          =  P E sin θ      [q(2l)= dipole moment P]                          =  P x E   Now ,  Torque (  τ  ) =  P E sin  θ  Work done to move a dipole in an external  elect...