question_answer

A drop of \[{{10}^{-6}}kg\] water carries \[{{10}^{-6}}C\] charge. What electric field should be applied to balance its weight (assume \[g=10m/{{s}^{2}})\]                                                                     [MP PET 2002]

A)            10 V/m upward                   

B)            10 V/m downward

C)            0.1 V/m downward           

D)            0.1 V/m upward

Correct Answer: A

Solution :

                     By using Þ \[E=\frac{mg}{Q}=\frac{{{10}^{-6}}\times 10}{{{10}^{-6}}}=10\,V/m;\] upward because charge is positive.