physics : class12 Field Due to Charge Assemblies : Superposition Principle : Electrostatics MCQ Questions and Answers
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Field Due to Charge Assemblies
MCQ questions and answers.
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MCQ Questions
1. According to the superposition principle, the net electric field at a point due to several charges is
A.
The algebraic sum of the electric fields due to each charge
B.
The vector sum of the electric fields due to each charge
C.
The electric field due to the largest charge only
D.
Always zero
Correct Answer:
The vector sum of the electric fields due to each charge
Explanation:
The electric field due to a charge assembly is obtained by adding the individual electric fields as vectors, taking both magnitude and direction into account.
2. Two equal positive charges are placed symmetrically on either side of a point. What is the net electric field at that point?
A.
Zero
B.
Directed toward the left charge
C.
Directed toward the right charge
D.
Equal to the field due to one charge
Correct Answer:
Zero
Explanation:
At the midpoint, the two equal charges produce electric fields of equal magnitude in opposite directions, so their vector sum is zero.
3. Two equal negative charges are placed symmetrically on either side of a point. The net electric field at the midpoint is
A.
Zero
B.
Directed away from both charges
C.
Directed toward the left charge
D.
Directed toward the right charge
Correct Answer:
Zero
Explanation:
The fields due to the two equal negative charges at the midpoint have equal magnitudes and opposite directions, so they cancel.
4. Two charges produce electric fields of 4 N/C and 3 N/C at a point in the same direction. What is the net electric field?
A.
1 N/C
B.
3 N/C
C.
5 N/C
D.
7 N/C
Correct Answer:
7 N/C
Explanation:
When electric fields are in the same direction, their magnitudes are added. Thus, the net field is 4 N/C + 3 N/C = 7 N/C.
5. Two charges produce electric fields of 6 N/C and 2 N/C at a point in opposite directions. What is the magnitude of the net electric field?
A.
2 N/C
B.
4 N/C
C.
8 N/C
D.
12 N/C
Correct Answer:
4 N/C
Explanation:
For opposite electric fields, the smaller magnitude is subtracted from the larger magnitude. Therefore, the net field is 6 N/C - 2 N/C = 4 N/C.
6. At a point, three charges produce electric fields of 2 N/C, 3 N/C, and 5 N/C in the same direction. The net electric field is
A.
5 N/C
B.
6 N/C
C.
8 N/C
D.
10 N/C
Correct Answer:
10 N/C
Explanation:
Since all three electric fields point in the same direction, their magnitudes add: 2 N/C + 3 N/C + 5 N/C = 10 N/C.
7. If the electric field at a point due to charge q1 is E1 and due to charge q2 is E2, the net field at that point is
A.
E1 - E2 only
B.
E1E2
C.
E1 + E2 as vectors
D.
E1 divided by E2
Correct Answer:
E1 + E2 as vectors
Explanation:
The electric field due to a combination of charges is found by vectorially adding the fields produced by the individual charges.
8. Two identical positive charges are placed at the ends of a straight line. At the midpoint, the electric field due to one charge is directed to the right. The field due to the other charge is directed
A.
To the right
B.
To the left
C.
Vertically upward
D.
Vertically downward
Correct Answer:
To the left
Explanation:
Electric field lines point away from positive charges. At the midpoint, the fields from the two identical positive charges point in opposite directions along the line joining them.
9. A charge assembly produces electric fields of equal magnitude in opposite directions at a point. The net electric field at that point is
A.
Twice either individual field
B.
Equal to one individual field
C.
Zero
D.
Infinite
Correct Answer:
Zero
Explanation:
Equal vectors acting in opposite directions cancel each other, giving a zero resultant electric field.
10. The electric field at a point due to a group of point charges is calculated by first finding
A.
Only the total charge, without considering positions
B.
The electric field due to each charge separately
C.
The mass of each charge
D.
The electric potential energy only
Correct Answer:
The electric field due to each charge separately
Explanation:
For a charge assembly, the field due to every charge is determined separately, and these individual fields are then added vectorially using the superposition principle.
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