Electrostatics 2 Question 22
23. A point charge $q$ moves from point $P$ to point $S$ along the path $P Q R S$ (Fig.) in a uniform electric field $E$ pointing parallel to the positive direction of the $X$-axis. The coordinates of points $P, Q, R$ and $S$ are $(a, b, 0)$, $(2 a, 0,0)(a,-b, 0)(0,0,0)$ respectively. The work done by the field in the above process is given by the expression ……
$(1989,2 \mathrm{M})$
Show Answer
Answer:
Correct Answer: 23. $-q E a$
Solution:
- $W_{F e}=\mathbf{F} \cdot \mathbf{d} \quad(\mathbf{d}=$ displacement $)$
$=(q E \hat{\mathbf{i}}) \cdot\left[\mathbf{r} _ {s}-\mathbf{r} _ {p}\right]=q E \hat{\mathbf{i}} \cdot[(-a \hat{\mathbf{i}}-b \hat{\mathbf{j}})]=-q E a$
