Single Choice

A spherical conductor of radius 10 cm has a charge of $$3.2 \times 10^{-7} C$$ distributed uniformly. What is the magnitude of electric field at a point $$15 cm$$ from the centre of the sphere? $$\left(\dfrac{1}{4\pi \in_0} = 9\times 10^9 Nm^/C^2\right)$$

A$$1.28 \times 10^5 N/C$$
Correct Answer
B$$1.28 \times 10^6 N/C$$
C$$1.28 \times 10^7 N/C$$
D$$1.28 \times 10^4 N/C$$

Solution

The charge present inside the sphere is $$q=3.2\times10^{-7}C$$
The electric field is to be determined at a point at $$r=15\ cm$$

Since the point is outside the sphere, the electric field can be obtained by considering the point charge of same magnitude at the distance of $$15\ cm$$ from the sphere as the whole charge is concentrated at the center.

The electric field is given by:
$$E=\dfrac{1}{4\pi\epsilon_o}\dfrac{q}{r^{2}}$$

Substitute the values:
$$E=9\times 10^9\times\dfrac{3.2\times 10^{-7}}{0.0225}$$

$$E=1.28\times10^5NC^{-1}$$

SIMILAR QUESTIONS

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