A block of mass ' m ' and charge ' q ' is connected to a point ' O ' with an inextensible string. This system is on a horizontal table. An electric field (E) is applied perpendicular to the string an…

Question

A block of mass ' m ' and charge ' q ' is connected to a point ' O ' with an inextensible string. This system is on a horizontal table. An electric field (E) is applied perpendicular to the string and in the plane of the horizontal table. The tension in the string when it becomes parallel to the electric field is

Accepted Answer

Correct answer: D. (d) Let the length of the string is L Using the work energy theorem F .L .= 12mv^2-0 qE .L= 12mv^2 ⇒v^2= 2 qELm If T is the tension in the string. When it becomes parallel to the electric field. T- qE= mv^2L ⇒T= qE+ mv^2L = qE+ mL 2 qELM ;T=3 qE

Solution

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