Short Answer TypeAn isolated 16 μF parallel plate air capacitor has a potential differences of 1000 V (Figure 5 a). A dielectric slab having relative permittivity (i.e. dielectric constant) = 5 is introduced to fill the space between the two plates com pletely. (Figure 5 b). Calculate:
(i) The new capacitance of the capacitor.
(ii) The new potential differences between the two plates of the capacitor
An electron revolves around the nucleus of hydrogen atom in a circular orbit of radius 5 x 10-11 m. Calculate
(i) Intensity of electric field of the nucleus at the position of the electron.
(ii) Electrostatic potential energy of the hydrogen nucleus and electron system.
In the circuit shown below, PQ is a uniform metallic wire of length 4 m and resistance 20 Ω. Battery B has an emf of 10V and internal resistance of 1 Ω. J is a jockey or slide contact. Resistance of the ammeter and connecting wires is negligible.
(i) When the jockey J does not touch the wire PQ, what is the reading of ammeter A?
(ii) Where should the jockey J be pressed on the wire PQ so that the galvanometer G shows no deflection?
Current density: It is defined as the electric current per unit cross sectional area (area normal to current) at any point in a conductor.
J = I / A
S.I unit is A m-2
The vector equation connectivity current density j with electric field intensity E for ohm conductor is as following:
Where 
is the conductivity.
is kept in two uniform and perpendicular magnetic fields 
as shown below:
(i) What is the effect of each of the magnetic fields
on the needle?
(ii) When the needle is in equilibrium, obtain an expression for an angle θ made by the needle with 
in terms 
of only.
at a point M which lies exactly midway between PQ and RS. 
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