Physics · Electric potential and its calculation for a point charge, electric dipole and system of charges
A charge of is kept at a distance of from a charge of . Find the two points wher
A charge of \( +4 \mu C \) is kept at a distance of \( 50 \mathrm{cm} \) from a charge of \( -6 \mu C \). Find the two points where the potential is zero
- A. Internal point lies at a distance of \( 20 \mathrm{cm} \) from \( 4 \mu \mathrm{C} \) charge and external point lies at a distance of \( 100 \mathrm{cm} \) from \( 4 \mu C \) charge
- B. Internal point lies at a distance of \( 30 \mathrm{cm} \) from \( 4 \mu C C \) charge and external point lies at a distance of \( 100 \mathrm{cm} \) from \( 4 \mu C \) charge
- C. Potential is zero only at \( 20 \mathrm{cm} \) from \( 4 \mu \mathrm{C} \) charge between the two charges
- D. Potential is zero only at \( 20 \mathrm{cm} \) from \( -6 \mu \mathrm{C} \) charge between the two charges
Step-by-step solution
For two charges q1=+4 μC and q2=-6 μC separated by 50 cm, the potential is zero at points on the line joining them where k(q1/r1 + q2/r2) = 0. Between the charges, solving q1/x = |q2|/(d-x) gives x = (q1/|q2|)d/(1+q1/|q2|) = (4/6)*50/(1+4/6) = (2/3)*50/(5/3) = 20 cm from the +4 μC charge. Outside, on the side of the smaller charge, solving q1/x = |q2|/(d+x) gives x = d * q1/(|q2|-q1) = 50 * 4/(6-4) = 100 cm from the +4 μC charge. Thus two points exist.
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