Two charges, one of which is Q1 = 3 μC and second one Q2 = -1 μC are separated by 100cm. The electric potential is zero at a point:
Correct answer: A. 25cm from Q2
- A. 25cm from Q2
- B. 75cm from Q2
- C. 50cm from Q1
- D. 33.3cm from Q1
Explanation
The electric potential is defined as the amount of work energy needed to move a unit of electric charge from a reference point to a specific point in an electric field. For two opposite charges of unequal magnitudes, the electric potential is zero at a point where the charges have canceled each other out. The mathematical formula for electric potential is V = kQ/r. The electric potential for two-point charges is V = V1 + V2.Let potential is zero at a distance x from 3μC⇒ k(3) / x + k(-1) / (100-x) = 0⇒ 3 / x = 1 / (100-x)⇒ 3(100-x) = 1(x)⇒ 300-3x = x⇒ 300 = x + 3x⇒ 300 = 4x⇒ x = 300/4⇒ x = 75Therefore, from a distance of 100-75 = 25 cm from Q2, the electric potential is zero.Diagram:
Last updated
About Electrostatics
Electrostatics describes forces between charges through Coulomb's law, electric fields and field intensity, then uses electric potential to measure energy per unit charge. Capacitors store charge and electrical energy, with capacitance depending on geometry and dielectric material, not simply on the amount of charge present.
Practise Electrostatics
831 free Electrostatics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 15 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
1/C_eq = 1/C_1 + 1/C_2 + 1/C_3 + ... + 1/C_n
1 N/C equals to:
1 volt x 1 ampere is equal to:
10 V potential difference is applied across the plate of the 1 µF capacitor. What is the energy stored in the capacitor?
12 J work is to be done against an existing electric field to take a charge of 0.01C from A to B. Find the potential difference between B and A: