Physics

Physics

LONG ANSWER QUESTIONS OF 5 MARKS EACH
Q.1. Find expression for the force and torque on an electric dipole kept in a uniform electric field .
Q.2. Find an expression for the maximum torque acting on an electric dipole when it is placed in a uniform electric field .
Q.3. An electric dipole is held in a uniform electric field (i) using suitable diagram show that it does not undergo any translatory motion , and (ii) derive an expression for the  torque acting on it and specify its direction .
Q.4.An electric dipole of dipole moment p is placed in a uniform electric field E . Write the expression for the torque τ experienced by the dipole . Identify the pairs of perpendicular vectors in the expression . Show diagrammatically the orientation of the dipole in the field for which the torque is (i) maximum (ii) half of the maximum value (iii) zero .
Q.5. Find an expression for the work done in rotating an electric dipole in a uniform electric field .
Q.6.Find an expression for the electric field strength at a distant point situated (i) on the axis and (ii) along the equatorial line of an electric dipole .
Q.7.Derive an expression for the electric potential due to an electric dipole at any point on its axis . Mention the contrasting features of electric potential of a dipole at a point as compared to that due to a single charge .
Q.8. (i) Using Gauss Theorem show mathematically that for any point out side the shell , the field due to a uniformly charged spherical shell is same as the entire charged shell is concentrated at the centre . (ii) Why do you expect the electric field inside the shell to be zero according to this theorem .
Q.9. State Gauss Theorem in Electrostatics . Apply it to find the electric field strength near an infinite plane sheet of charge .

Q.10. Apply Gauss Theorem to obtain the expression for the  electric field at a point due to an infinitely long , thin , uniformly charge straight wire of linear charge density  λ Cm^-1 .