A point charge of magnitude $+ 3, μ C$ is placed at the origin. Calculate the electric potential at a point $P$ located $15, cm$ from the charge. Take the potential to be zero at infinity. Use $k = 9 \times 1 0^{9}, N m^{2} C^{- 2}$ .

easy 2 marks Class 12 · Physics · Electrostatic Potential and Capacitance

Answer

1.80 \times 1 0^{5}, V

The correct answer is $1.80 \times 1 0^{5}, V$ — Carry out the multiplication and division: $9 \times 1 0^{9} \times 3 \times 1 0^{- 6} = 27 \times 1 0^{3}$ , then $27 \times 1 0^{3} /0.15 = 1.8 \times 1 0^{5}, V$ .

Step-by-step solution

Convert the given distance from centimeters to meters: $15 cm = 0.15 m$ .
Write the formula for electric potential due to a point charge: $V = \frac{k q}{r}$ .
Substitute the numerical values: $V = \frac{( 9 \times 1 0 ^{9} ) ( 3 \times 1 0 ^{- 6} )}{0.15}$ .
Carry out the multiplication and division: $9 \times 1 0^{9} \times 3 \times 1 0^{- 6} = 27 \times 1 0^{3}$ , then $27 \times 1 0^{3} /0.15 = 1.8 \times 1 0^{5}, V$ .

Common mistake: Not converting distance to meters before using

k

Concept tested: Point charge electric potential

Published 16 September 2026 · How this solution was prepared and checked

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A point charge of magnitude +3,μC is placed at the origin. Calculate the electric potential at a point P located 15,cm from the charge. Take the potential to be zero at infinity. Use k=9×109,N m2C−2.

Step-by-step solution

A point charge of magnitude $+ 3, μ C$ is placed at the origin. Calculate the electric potential at a point $P$ located $15, cm$ from the charge. Take the potential to be zero at infinity. Use $k = 9 \times 1 0^{9}, N m^{2} C^{- 2}$ .