Point charge q moves from point P to point S along path PQRS (figure shown) in a uniform electric fi

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1. Electric Charges and Fields

hard

Point charge $q$ moves from point $P$ to point $S$ along the path $PQRS$ (figure shown) in a uniform electric field $E$ pointing coparallel to the positive direction of the $X - $axis. The coordinates of the points $P,\,Q,\,R$ and $S$ are $(a,\,b,\,0),\;(2a,\,0,\,0),\;(a,\, - b,\,0)$ and $(0,\,0,\,0)$ respectively. The work done by the field in the above process is given by the expression

$qEa$

$ - qEa$

$qEa\sqrt 2 $

$qE\sqrt {[{{(2a)}^2} + {b^2}]} $

(IIT-1989)

Solution

(b)As electric field is a conservative field
Hence the work done does not depend on path
${W_{ABCD}} = {W_{AOD}}$ $ = {W_{AO}} + {W_{OD}}$
$= Fb \,cos \,90^o + Fa\, cos \,180^o = 0 + qEa (-1)= -qEa$

Standard 12

Physics

Two point charges $3 \times 10^{-6} \,C$ and $8 \times 10^{-6} \, C$ repel each other by a force of $6 \times 10^{-3} \, N$. If each of them is given an additional charge $-6 \times 10^{-6} \, C$, the force between them will be

easy

Select the correct alternative

medium

The ratio of electrostatic and gravitational forces acting between electron and proton separated by a distance $5 \times {10^{ – 11}}\,m,$ will be (Charge on electron $=$ $1.6 \times 10^{-19}$ $C$, mass of electron = $ 9.1 \times 10^{-31}$ $kg$, mass of proton = $1.6 \times {10^{ – 27}}\,kg,$ $\,G = 6.7 \times {10^{ – 11}}\,N{m^2}/k{g^2})$

hard

In a medium, the force of attraction between two point charges, distance $d$ apart, is $F$. What distance apart should these point charges be kept in the same medium, so that the force between them becomes $16\, F$ ?

easy

Two small spheres each of mass $10 \,mg$ are suspended from a point by threads $0.5 \,m$ long. They are equally charged and repel each other to a distance of $0.20 \,m$. The charge on each of the sphere is $\frac{ a }{21} \times 10^{-8} \, C$. The value of $a$ will be …… .

$\left[\right.$ Given $\left.g=10 \,ms ^{-2}\right]$

hard

(JEE MAIN-2021)

Solution

Similar Questions

Two point charges $3 \times 10^{-6} \,C$ and $8 \times 10^{-6} \, C$ repel each other by a force of $6 \times 10^{-3} \, N$. If each of them is given an additional charge $-6 \times 10^{-6} \, C$, the force between them will be

Select the correct alternative

In a medium, the force of attraction between two point charges, distance $d$ apart, is $F$. What distance apart should these point charges be kept in the same medium, so that the force between them becomes $16\, F$ ?

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