Two point charges of +5 C and -12 C attract each other with a force of 1.48 N. If charge of -5 C is added to each of these charges. Now the force will be:
Correct answer: D. Zero
- A. 1.48 N (attractive)
- B. 1.48 N (repulsive)
- C. 2.96 (repulsive)
- D. Zero
Explanation
The charges after adding -5C become:Q1 = +5-5 = 0CQ2 = -12-5 = -17CUsing formulaF= kq1q2/r21.48 = 9(109) (0)(17)/r2Since one charge is 0C, by muliplying it with other values the force will become zero.
This question appeared on the NUMS 2015 paper, which you can sit online with every answer explained.
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About Coulomb's Law
Coulomb's law gives the electrostatic force between two point charges in terms of their magnitudes, separation and the medium between them. Questions involve attraction and repulsion, the inverse square relationship, superposition of forces and vector direction, which must not be confused with the electric field produced by a charge.
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