Question: Two point charges of +3 μC and -3 μC are placed 1 m apart. What is the electric potential at the midpoint?
Options:
0 V
9 × 10^9 V
4.5 × 10^9 V
None of the above
Correct Answer: 0 V
Solution:
The potentials due to both charges at the midpoint cancel each other, so V = 0 V.
Two point charges of +3 μC and -3 μC are placed 1 m apart. What is the electric
Practice Questions
Q1
Two point charges of +3 μC and -3 μC are placed 1 m apart. What is the electric potential at the midpoint?
0 V
9 × 10^9 V
4.5 × 10^9 V
None of the above
Questions & Step-by-Step Solutions
Two point charges of +3 μC and -3 μC are placed 1 m apart. What is the electric potential at the midpoint?
Step 1: Identify the two point charges. We have a positive charge of +3 μC and a negative charge of -3 μC.
Step 2: Determine the distance between the two charges. They are placed 1 meter apart.
Step 3: Find the midpoint between the two charges. The midpoint is 0.5 meters from each charge.
Step 4: Calculate the electric potential due to the positive charge at the midpoint. The formula for electric potential (V) is V = k * Q / r, where k is a constant (approximately 8.99 x 10^9 N m²/C²), Q is the charge, and r is the distance from the charge to the point.
Step 5: Calculate the electric potential due to the negative charge at the midpoint using the same formula.
Step 6: Notice that the positive charge creates a positive potential and the negative charge creates a negative potential at the midpoint.
Step 7: Since the magnitudes of the potentials from both charges are equal but opposite in sign, they cancel each other out.
Step 8: Conclude that the total electric potential at the midpoint is 0 V.
Electric Potential – The electric potential at a point in space due to a point charge is given by V = k * q / r, where k is Coulomb's constant, q is the charge, and r is the distance from the charge to the point.
Superposition Principle – The total electric potential at a point due to multiple charges is the algebraic sum of the potentials due to each charge.
Midpoint Calculation – When two equal and opposite charges are equidistant from a point, their potentials at that point will cancel each other out.
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