Electric Field - Electric Field Intensity Due to a Point-Charge

A particle of charge q and mass m moves rectilinearly under the action of electric field E = A – Bx, where A and B are positive constants and x is distance from the point where particle was initially at rest then the distance traveled by the particle before coming to rest and acceleration of particle at that moment are respectively.

The bob of a simple pendulum has a mass of 40 g and a positive charge of 4.0 × 10⁻⁶ C. It makes 20 oscillations in 45 s. A vertical electric field pointing upward and of magnitude 2.5 × 10⁴ NC⁻¹ is switched on. How much time will it now take to complete 20 oscillations? 

What is the amount of work done in moving a point charge Q around a circular arc of radius ‘r’ at the centre of which another point charge ‘q’ is located?

Consider two identical point charges located at points (0, 0) and (a, 0).

Is there a point on the line joining them at which the electric potential is zero?

A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from the centre is directed ______.

Assertion: On moving a distance two times the initial distance away from an infinitely long straight uniformly charged wire the electric field reduces to one-third of the initial value.

Reason: The electric field is inversely proportional to the distance from an infinitely long straight uniformly charged wire.