One of the sections of physics which are the cornerstone of knowledge devoted to the processes connected with electricity is the electrostatics. She studies interaction of motionless electric charges. Therefore one of typical tasks which can be required to solve to school students and junior students of HIGHER EDUCATION INSTITUTIONS is finding of tension between condenser plates on the basis of knowledge of various parameters.
It is required to you
- - knowledge of capacity or geometrical and physical parameters of the condenser;
- - knowledge of energy or a charge on the condenser.
Instruction
1. Find tension between condenser plates if the current size of the energy which is saved up by it and also its capacity is known. The energy reserved by the condenser can be calculated on a formula W= (C∙U²)/2 where C - capacity, and U - tension between plates. Thus, the value of tension can be received as a root from the doubled value of energy divided into capacity. That is, it will be equal: U= √ (2∙W/C).
2. The energy reserved by the condenser can be also calculated on the basis of value of the charge (quantity of electricity) which is contained in it and tension between facings. The formula setting compliance between these parameters has an appearance: W=q∙U/2 (where q is a charge). Therefore, knowing energy and a charge of the condenser, it is possible to calculate tension between its plates on a formula: U=2∙W/q.
3. As the charge on the condenser is proportional as tension attached to its plates, and the device capacity (it is defined by a formula q=C∙U), knowing a charge and capacity, it is possible to find also tension. Respectively, for carrying out calculation use a formula: U=q/C.
4. For obtaining value of tension on the condenser with the known geometrical and physical parameters, at first calculate its capacity. For the simple flat condenser consisting of two carrying-out plates divided by dielectric between which distance is negligible in comparison with their sizes the capacity can be calculated on a formula: C= (ε ∙ε0∙S) / d. Here d - distance between plates, and S - their area. Value ε0 - an electric constant (the constant equal 8,8542•10^-12 of F/m), ε - relative dielectric permeability of space between plates (she can be recognized from physical reference books). Having calculated capacity, calculate tension one of the methods given in steps 1-3.