BDS Learning Application (RS)

  Electric Charges and Fields      Problems   Question1.   What is the value of charge on an electron? Is a charge less than this value possible? Solution.   e = - 1.6 x 10-19 C.                 No, charge less than this value do not exist.   Question2. Does the motion of a body affect its charge?   Solution. No, charge on a body does not change with the motion of the body. Question3. Give two points of distinction between charge and mass. Solution. The charge can be positive, negative, or zero. But mass is a positive quantity. Further, the electric charge is always conserved. But mass is not conserved as it can be changed into energy and vice-versa. Question4. What is the basic cause of the quantization of charge? Solution. Only integral a number of electrons can be transferred from one body to the other. Question5. Can ever photons have a charge? If not why? Solution. No, photons can never have a charge. This is because charge cannot exist without rest ma

  Electric Charges and Fields      Problems Question1. Give some points of dissimilarity and similarity between electrostatic forces and gravitational forces.   Solution. (a) Dissimilarity   1. Electrostatic forces are between two charges and gravitational forces are between two masses.   2. Electrostatic forces may be attractive or repulsive. But gravitational forces are always attractive. 3. Electrostatic force between two protons is 10 -36 times stronger than the gravitational force between them. 4. Electrostatic forces operate over distances which are not large. Gravitational forces operate over very large distances. 5. Electrostatic force depends on the medium between the two charges. Gravitational force does not depend upon the medium between the two masses.   (b) Similarity . 1. Both the forces obey inverse square law.   2. Both forces are proportional to the product of charges (or masses) of interacting particles.   3. Both are central forces. 4. Bot

  Electric Charges and Fields      Problems Question1. Two free protons and two free electrons are separated by the same distance. Compare coulomb’s forces of repulsion between the pair of protons and pair of electrons. Solution. The forces are the same because each proton carries a charge of the same magnitude as each electron and the distance between them is the same. Question2. A charge Q is kept in the inner cavity and a charge 2Q is given to the inner shell. A charge 3Q is given to the outermost shell, as shown in the given figure. Find the charges at the surfaces A, B, and C. Solution. Due to induction, -Q charge is induced on the inner surface A of the inner shell and +Q charge is induced on the outer surface B of the outer shell. Thus charge on the surface A= -Q.                                                                                                                           Now charge on surface B = 2Q + Q = 3Q  Due to induction, - 3Q charge is induced on the in

  Electric Charges and Fields   17-    Problems Question1. A particle carrying charges +q is held at the center of a square of each side one meter. It is surrounded by eight charges arranged on the square as shown in the figure. If q= 2 μC, what is the net force on the particle? Solution. As is clear from figure, force on the particle at 0 due to (-2q, -2q); (-3q,-3q) and (+4q, +4q) are equal and opposite. They cancel out in pairs. However, the force due to +7q and -7q add up. Therefore, the net force on the particle at 0 is Question2. Coulomb’s law for the electrostatic force between two point charge and Newton’s law for gravitational force between two stationary point masses, both have an inverse square dependence on the distance between the charges/masses. (a) Compare the strength of these forces by these forces by determining the ratio of their magnitude (1) for an electron and a proton (2) for two protons (b) Estimate the acceleration for electron and proton due to the electrical