physics : class12 Electric Field Due to Multiple Charges : Superposition Principle : Electrostatics MCQ Questions and Answers
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Electric Field Due to Multiple Charges
MCQ questions and answers.
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MCQ Questions
1. Two electric charges produce electric fields of 3 N/C and 4 N/C at a point, and both fields act in the same direction. What is the net electric field?
A.
1 N/C
B.
7 N/C
C.
12 N/C
D.
0.75 N/C
Correct Answer:
7 N/C
Explanation:
When electric fields due to multiple charges act in the same direction, their magnitudes are added. Thus, the net field is 3 N/C + 4 N/C = 7 N/C.
2. At a point, two charges produce electric fields of 10 N/C and 6 N/C in opposite directions. What is the magnitude of the net electric field?
A.
4 N/C
B.
16 N/C
C.
60 N/C
D.
1.67 N/C
Correct Answer:
4 N/C
Explanation:
Oppositely directed electric fields combine by subtraction. Therefore, the net field magnitude is 10 N/C − 6 N/C = 4 N/C.
3. The electric field at a point due to three charges is found by
A.
Adding the charges algebraically and then finding one field
B.
Adding the electric field vectors due to each charge
C.
Multiplying the three individual electric fields
D.
Using only the field due to the largest charge
Correct Answer:
Adding the electric field vectors due to each charge
Explanation:
The superposition principle states that the total electric field is the vector sum of the fields produced by all individual charges.
4. Two identical positive charges are placed symmetrically on either side of a midpoint. What is the net electric field at the midpoint?
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 identical charges produce electric fields of equal magnitude in opposite directions. Their vector sum is therefore zero.
5. A point is equidistant from two identical positive charges. The electric field due to each charge at that point has magnitude E, and the two fields are perpendicular. What is the magnitude of the net electric field?
A.
E
B.
2E
C.
E divided by 2
D.
E times the square root of 2
Correct Answer:
E times the square root of 2
Explanation:
For two perpendicular electric field vectors of equal magnitude E, the resultant magnitude is found using the Pythagorean theorem: square root of (E² + E²) = E times the square root of 2.
6. If the electric fields due to two charges at a point are 5 N/C east and 5 N/C west, what is the resultant electric field?
A.
10 N/C east
B.
10 N/C west
C.
5 N/C east
D.
0 N/C
Correct Answer:
0 N/C
Explanation:
The two fields have equal magnitudes and opposite directions, so their vector sum is zero.
7. At a point, three charges produce electric fields of 2 N/C, 3 N/C, and 4 N/C, all in the same direction. What is the total electric field?
A.
1 N/C
B.
5 N/C
C.
9 N/C
D.
24 N/C
Correct Answer:
9 N/C
Explanation:
Since all three electric field vectors point in the same direction, their magnitudes are added: 2 N/C + 3 N/C + 4 N/C = 9 N/C.
8. At a point, the electric field due to charge q1 is 8 N/C north and that due to charge q2 is 3 N/C south. What is the net electric field?
A.
11 N/C north
B.
5 N/C north
C.
5 N/C south
D.
24 N/C north
Correct Answer:
5 N/C north
Explanation:
The fields act in opposite directions, so their magnitudes are subtracted. The larger field is northward, giving 8 N/C − 3 N/C = 5 N/C north.
9. If the electric field at a point due to charge q1 is E1 and due to charge q2 is E2, the total electric field is
A.
E1 + E2 as ordinary numbers only
B.
E1 − E2 in every situation
C.
The vector sum of E1 and E2
D.
E1 multiplied by E2
Correct Answer:
The vector sum of E1 and E2
Explanation:
Electric field is a vector quantity. Therefore, the total field due to multiple charges is obtained by adding the individual electric fields vectorially.
10. According to the superposition principle, the net electric field at a point due to several charges is
A.
The product of the electric fields due to all charges
B.
The vector sum of the electric fields due to all charges
C.
The scalar sum of the magnitudes of all charges
D.
The electric field due to the largest charge only
Correct Answer:
The vector sum of the electric fields due to all charges
Explanation:
The electric field due to multiple charges is found by adding the electric field vectors produced by each charge separately.