Q1. What is the potential energy of two charges +3 μC and +4 μC separated by 0.2 m? (2023)
Solution:
Potential energy U = k * q1 * q2 / r = (9 × 10^9 N m²/C²) * (3 × 10^-6 C) * (4 × 10^-6 C) / 0.2 m = 54 J.
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Q2. A charge of +5 μC is placed in an electric field of 1000 N/C. What is the work done in moving the charge 0.2 m in the direction of the field? (2022)
Solution:
Work done W = F * d = (E * q) * d = (1000 N/C * 5 × 10^-6 C) * 0.2 m = 0.1 J.
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Q3. What is the electric field at a point due to a uniformly charged infinite plane sheet? (2020)
Solution:
The electric field due to an infinite plane sheet is E = σ/2ε₀ on both sides, but the total field is σ/ε₀.
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Q4. If a charge of +10 μC is placed in an electric field of strength 200 N/C, what is the force experienced by the charge? (2019)
Solution:
Force F = qE = (10 × 10^-6 C) * (200 N/C) = 2 N.
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Q5. In a uniform electric field, the potential difference between two points is 10 V. If the distance between these points is 2 m, what is the strength of the electric field? (2023)
Solution:
E = V/d = 10 V / 2 m = 5 N/C.
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Q6. What is the potential difference between two points in an electric field if the electric field strength is 50 N/C and the distance between the points is 0.4 m? (2023)
Solution:
Potential difference V = E * d = 50 N/C * 0.4 m = 20 V.
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Q7. What is the electric field due to a point charge of +10 µC at a distance of 0.1 m? (2023)
Solution:
Electric field E = k * |q| / r² = (9 × 10^9 N m²/C²) * (10 × 10^-6 C) / (0.1 m)² = 9000 N/C.
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Q8. If two identical charges are placed 1 m apart, what will be the electric field at a point midway between them? (2019)
Solution:
The electric fields due to both charges at the midpoint will cancel each other, resulting in a net electric field of 0 N/C.
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Q9. Two identical charges are placed 1 m apart. If the magnitude of each charge is doubled, what happens to the force between them? (2022)
Solution:
According to Coulomb's law, F ∝ q1 * q2. If both charges are doubled, the force becomes 4 times the original force.
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Q10. What is the electric field at a distance of 1 m from a charge of -4 μC? (2019)
Solution:
E = k * |q| / r² = (9 × 10^9 N m²/C²) * (4 × 10^-6 C) / (1 m)² = 3600 N/C, directed towards the charge.
