a block of mass m andhaving a charge q is placed on a smooth horizontal table and is connected to a wall through an unstressed spring of spring constant k.A horizontal electric field E parallel to the spring is switched on.find the amplitude of the resulting SHM of the block----

ans:_ qE/k

two identical balls ,each having a charge of 2.00x10^-7c  and a mass of 100g,are suspended from a common point by two insulating strings each 50cm long.the ballsare held at a separation of 5.0cm apart and then released.find

1. the components of the resultant force on it along and perpendicular to the string


2. the tension in the string


3. the accelaration of one of the balls.answers are to be obtained only for the instant just after the release

ans.:-

1. zero,0.095N away from the other charge


2. 0.986N


3. 0.95m/s2 perpendicular to the string and going away from the other charge

an electric field E with an average magnitude of about 150N/C points upward in the earth's atmosphere.We wish to "float" a sulfur sphere weighing 1.0lb in this field by charging it.

(a)what charge and  magnitude must be used?

(b)why is the experiment not practical?Give a qualitative reason supported by a very rough numerical calculation to prove ur point.

consider a point charge at a distance r from the centre of the dipole along its axis.show that at large values of r,the electric field is

E=(0) x (p/r³)

estimate roughly the no. of coulombs of positive charges in a glass of water.

protons i the cosmic rays strike the earth's upper atmosphere at a rate,averaged over the earth's surfaceof 0.15 protons.cm2-sec.what total current does the earth recieve from beyond its atmosphere in the form of incident cosmic ray protons ?the earth's radius is 6.4x10⁶m.