Chapter 1
71 Maths Exercise Solutions
If 
electrons move out of a body to another body every second, how much time is required to get a total charge of 
on the other body?
electrons move out of a body to another body every second, how much time is required to get a total charge of on the other body? Coulomb’s law for electrostatic force between two point charges and Newton’s law for gravitational force between two stationary point masses, both have inverse-square dependence on the distance between the charges/masses. Compare the strength of these forces by determining the ratio of their magnitudes for an electron and a proton and for two protons. 
Coulomb’s law for electrostatic force between two point charges and Newton’s law for gravitational force between two stationary point masses, both have inverse-square dependence on the distance between the charges/masses.
Estimate the accelerations of electron and proton due to the electrical force of their mutual attraction when they are
apart? 
Estimate the accelerations of electron and proton due to the electrical force of their mutual attraction when they are
apart? A charged metallic sphere 
is suspended by a nylon thread. Another charged metallic sphere 
held by an insulating handle is brought close to such that the distance between their centres is 
, as shown in figure. The resulting repulsion of is noted (for example, by shining a beam of light and measuring the deflection of its shadow on a screen). Spheres and are touched by uncharged spheres 
and 
respectively, as shown in figure. and are then removed and is brought closer to to a distance of 
between their centres, as shown in figure. What is the expected repulsion of on the basis of Coulomb’s law? Spheres and and spheres and have identical sizes. Ignore the sizes of and in comparison to the separation between their centres.
is suspended by a nylon thread. Another charged metallic sphere held by an insulating handle is brought close to such that the distance between their centres is , as shown in figure. The resulting repulsion of is noted (for example, by shining a beam of light and measuring the deflection of its shadow on a screen). Spheres and are touched by uncharged spheres and respectively, as shown in figure. and are then removed and is brought closer to to a distance of between their centres, as shown in figure. What is the expected repulsion of on the basis of Coulomb’s law? Spheres and and spheres and have identical sizes. Ignore the sizes of and in comparison to the separation between their centres.Consider three charges 
each equal to 
at the vertices of an equilateral triangle of side 
. What is the force on a charge 
with the same sign as 
placed at the centroid of the triangle, as shown in figure.
each equal to at the vertices of an equilateral triangle of side . What is the force on a charge with the same sign as placed at the centroid of the triangle, as shown in figure. Consider the charges 
and 
placed at the vertices of an equilateral triangle, as shown in figure. What is the force on each charge?
and placed at the vertices of an equilateral triangle, as shown in figure. What is the force on each charge?An electron falls through a distance of 
in a uniform electric field of magnitude 
The direction of the field is reversed keeping its magnitude unchanged and a proton falls through the same distance 
Compute the time of fall in each case. Contrast the situation with that of ‘free fall under gravity’.
in a uniform electric field of magnitude The direction of the field is reversed keeping its magnitude unchanged and a proton falls through the same distance Compute the time of fall in each case. Contrast the situation with that of ‘free fall under gravity’. Still Have Question?