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1. Electric Charges and Fields
easy
The electric field in a region is radially outward and at a point is given by $E=250 \,r V / m$ (where $r$ is the distance of the point from origin). Calculate the charge contained in a sphere of radius $20 \,cm$ centred at the origin ......... $C$
A
$2.22 \times 10^{-6}$
B
$2.22 \times 10^{-8}$
C
$2.22 \times 10^{-10}$
D
$0$
Solution
(c)
$E=\frac{1}{4 \pi \varepsilon_0} \cdot \frac{Q}{r^2}$
$250 r=\frac{9 \times 10^9 \cdot Q}{r^2}$
Use $r=20 \times 10^{-2} \,m$
Find $Q=$ ?
$Q=2.22 \times 10^{-10} C$
Standard 12
Physics
