Question

The kinetic energy of a charged particle decreases by 10 J as it moves from a point at potential 100 V to a point at potential 200 V. Find the charge on the particle.  

Answer 1

By work-energy theorem,
Change in K.E. = Amount of work done
Change in K.E. = 10 J
Let the charge on the particle be q.
Change in potential,

\[∆ V\]  = (200 − 100) V
Work done = \[∆ V \times q\]

\[\Rightarrow 10 = (200 - 100) \times q\]

\[ \Rightarrow 100 \times q = 10\]
\[ \Rightarrow q = \frac{10}{100} = 0 . 1 C\]