JEE PYQ: Electrostatics Question 17
Question 17 - 2020 (02 Sep Shift 2)
A small point mass carrying some positive charge on it, is released from the edge of a table. There is a uniform electric field in this region in the horizontal direction. Which of the following options then correctly describe the trajectory of the mass? (Curves are drawn schematically and are not to scale).
(1) Straight line
(2) Parabolic (opening toward field direction)
(3) Parabolic (opening away from field)
(4) Half-parabola then straight line
Show Answer
Answer: (4)
Solution
Net force $\vec{F} = qE\hat{i} + mg\hat{j}$ gives constant acceleration, so path is a straight line. The acceleration $a = \sqrt{(qE/m)^2 + g^2}$ at an angle. Since initial velocity is zero, the path is a straight line in the direction of net force. This matches option (4) showing the correct trajectory.
BETA
