Question

(i) If two similar large plates, each of area A having surface charge densities +σ  and - σ are separated by a distance d in  air, find the expressions for 

(a) field at points between the two plates and on outer side of the plates. 

Specify the direction of the field in each case. 

(b) the potential difference between the plates. 

(c) the capacitance of the capacitor so formed. 

(ii) Two metallic spheres of radii R and 2R are charged so that both of these have same surface charge density σ. If they are connected to each other with a conducting wire, in which direction will the charge flow and why ?

Answer 1

(a)The electric field at point between the plates and 

directed from positive plate to negative plate

(b)Potential difference V = E x separation between two plates

(c) Charge on capacitor : magnitude of charge on any of two plates

q =  σA

and potential difference

(ii) When two charged conducting metallic spheres are connected with a conducting wire, then charge flows between the two, till their potentials become equal or redistribution of charges takes place i.e., charge is equally divided on both the spheres