Physics, Chemistry, Mathematics Forums

i ahd a doubt::

if we make a circuit consisting of only a capacitor and nothing else. meaning thereby connecting the surfaces of the parallel plates  (the ones which do not form the capacitor) . what happens??

i think that nothing shoul happen but someone told me that it would get instantaneously discharged and there wuld be energy loss.

that got me confused pleeaeeese help...

A uniform solid cube of mass M has edge length a. The moment of inertia of the cube about its edge diagonal will be
(a) (3)^1/2/ 2 Ma² (b) 1 / 2 Ma² (c) 5 / 12 Ma² (d) 7 / 12 Ma²
The ans. is given as c, Please reply soon.

A conducting sphere S₁ of radius r is attached to an insulating handle. Another conducting sphere S₂  of radius R is mounted as an insulating stand S₂ is intially uncharged .S₁ is given a charge Q, brought into contact with S₂ and removed .S₁ is recharged such that the charge on it is again Q and is again brought into contact with S₂ and removed.The procedure is repeated n times.Find the electrostatic energy of S₂ after n such contacts with S_1.

as we can find the magnetic field due to V-shaped wire at any point.similarly,canwe find electric field.

what is the moment of inertia about the centre of rod of infinite length and about the centre of a hollow sphere of maximum volume?

Please reply soon.

When a capacitor is filled with dielectric slab and the capacitor is also connected to a battery,then due to dielectric slab,the potential difference across capacitor decreases but the decrease  in potential difference is taken into account by the battery .Battery tries to maintain the same potential difference .But if the potential difference is same across the capacitor as the previous one then why should capacitance increase ? I mean to say that we usually say that insertion of dielectric makes potential difference across the capacitor less and since Q=C/V, charge increases ,thus capacitance increases.Please reply,I am very confused.

Q. A transparent sphere of radius R and refractive index n is at rest on a horizontal surface. A ray of light is incident parallel to the vertical diameter and at a distance d from it.
a) Obtain an expression for d in terms of n and R such that the ray intersects the diameter at the point of emergence.
b) What is the allowed range of values of n for the above possibility to occur??

This ques. came in this year's Indian National Physics Oly. Plzzzz try solving this ques. and tell me the answer.

I got the answer as d = [nR(4-n²)^1/2]/2

and the allowed range of n as (1,2).

A capacitor of capacitance 5 microfarad is charged to 24 volts and another capacitor of capacitance 6 microfarad is charged to 12 volts. The positive plate of the first capacitor is now connected to negative plate of the second capacitor.Find new charges on the capacitor.  

Books give parallel translation of Biot Savart's law as:

B=ü₀/4(pie) q vXr/r³---------------(1)

Then with reference to our discussion on electricity by Vikas Agrawal dated 6 November 2006,

E=0 around conductor carrying current as there is no net charge inside a conductor.Similarly because of eq(1),B should be zero around conductor which is not really the case.Was our discussion wrong there or I am wrong here?

If the pressure of hydrogen gas is increased form 1 atm to 100 atm,keeping the temp. and hydrogen ion conc. same,the voltage of hydrogen half cell will change by:

a)0.059V                              b)0.59V

C)0.118V                              d)0.0295V

I don't want answer I just want you all to tell me that while applying E=E⁰-RT/nF ln(Q) , this Q is Qc or Qp.In other words,should we Consider[H+] or  [H₂] in this eq.