Electrostatics - Short Question and Answer

Electrostatics - Short Question and Answer Points : Electrostatics-Short Question and Answer Q. 1. Does electric potential enhance or decrease along an electric line of force? Ans. The electric field amount acts in direction of electric line of force. We know that, E = - dVI dr. This means that in direction of electric field amount, potential decreases. It is similar thing as potential decreases along an electric line of force. Q. 2. While ordinary rubber is insulator, the rubber tyres of air craft are made slightly conducting. Why? Ans. During the take off and landing, the friction among tyres and the nm-way causes electrification of tyres. lithe tyres are non-conducting, extreme charge will accumulate on the tyres which might cause sparking. If material of the tyres is faintly conducting, the accumulate charge can flow to earth, therefore eliminting any hazard of fire. Q.3. Electrostatic experiments cannot be conduct effectively on humid days. Explain. Ans. The humid air becomes conducting. Therefore, the static charge on the apparatus leaks off to the air. For this reason, electrostatic experiment do not work well on humid days. Q. 4. What do you understand through a point charge? Ans. Charged bodies approximate to point charges if their sizes are small compare to distance among them. Q. 5. Can two equipotential surfaces intersect each other? Ans. No. The intersection of two equipotential surfaces means that at point of intersection, there are two values of potential which is not possible. Alternatively electric lines of force are normal to equipotential surfaces. If two equipotential surfaces intersect each other, it means that electric field at point of intersection has two directions which is not feasible. Q. 6. What similarities do electrostatic forces have to gravitational forces ? Q. 6. What similarities do electrostatic forces have to gravitational forces ? Ans. (i) Both are conservative forces, ie., work done by them does not depend upon the path followed.
(ii) Both obey inverse square law.
(iii) Both involve a property of the interacting particles the mass in one case and the charge in the other.
(iv) Both are central forces, i.e., forces act along the lines joining the centres of the bodies. Q. 7. Any conducting object attached to earth is said to be grounded, Explain. Ans. Because earth is a very big source of electrons or sink. Its possible remains constant whether electrons are given to it or removed as of it. For this reason, electric potential of earth is assumed zero. Q. 8. Vehicles carrying inflammable materials frequently have chains that hang down and drag on the ground. Why? Ans. When a vehicle is in motion, its tyres rub against the road and gets charged suitable to friction more, due to friction of air, body of vehicle too gets charged. If accumulate charge becomes extreme, sparking may happen and the inflammable material may catch fire. Since chain ropes are touching the ground, charge leaks to earth. Hence, the danger of fire is avoid. Q:9. Metallic sphere is charged negatively. Will its mass raise, decrease or remain the similar? Ans. When sphere is negatively charged, it means electrons have been extra to it. As electrons have finite mass, mass of negatively charged sphere will raise. Q. 10. You cannot disturb electrical impartiality of ordinary matter extremely much. Explain. Ans. Below ordinary conditions, a body is electrically neutral, i.e., it has similar amounts of positive charge and negative charge. As a body is charged (positively or negatively), this electrical neutrality is disturbed. Suppose you are charging a body positively by removing electrons as of it. The positive charge on body tends to pull negative charge (i.e., electrons) back. As the body gets more and more positive charge, the electrostatic force tending to pull the negative charge back also increases. Thus, we cannot place a large charge (positive or negative) on a body. Q. 11. Why is electric current and not charge taken as fundamental amount in SI units? Ans. For practical reasons, electric current and not charge has been in use as the fundamental amount, although one is derivable as of the other ( q = It). The significant thought which led to the selection of current as the fundamental quantity is that it serves as the link among electric, magnetic and mechanical quantities and can be eagerly measured. Q. 12. While you run comb through hair it attracts bits of paper. Why? What would you expect if hair is wet or f it is a rainy day? Ans. While we run comb through hair, comb gets charged due to friction and as a consequence it attracts bits of paper. If hair is wet, friction among comb and hair is really reduced. Thus, tomb is charged to a lesser amount and it may not attract the bits of the paper. The similar is true if it is a rainy day. It is because due to superior humidity, the hair do not stay completely dry. Q. 13. -Electric potential at a point is 10 V. What do you signify by it? Ans. It means that if we place a charge of I C at that point, charge will have a potential energy of 10 J. equally, if we place a charge of 2 C, charge will have a potential energy of 20 J. Note that potential energy per unit charge (i.e., electric potential) is 10 V. Q. 14. Can electric potential at a point be zero as electric intensity at that point is nor zero ? Ans. Yes. The electric potential on the perpendicular bisector of an electric dipole is zero as electric intensity is not zero. Q. 15. How do we signify the electric potential field geometrically? Ans. An electric field is represented geometrically by electric lines of force. However, electric potential field is represent geometrically through equipotential surfaces. Note that in an electric field, there is a unique value of potential at each point. Thus, there exists electric potential field.