physics : class12 Vector Addition of Electric Fields : Superposition Principle : Electrostatics MCQ Questions and Answers
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Vector Addition of Electric Fields
MCQ questions and answers.
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MCQ Questions
1. Two electric fields of magnitudes 3 N/C and 4 N/C act in the same direction at a point. What is the resultant electric field?
A.
1 N/C
B.
7 N/C
C.
12 N/C
D.
4 N/C
Correct Answer:
7 N/C
Explanation:
For electric fields acting in the same direction, their magnitudes are added: E = 3 + 4 = 7 N/C.
2. Two electric fields of magnitudes 8 N/C and 3 N/C act in opposite directions at a point. What is the magnitude of the resultant electric field?
A.
11 N/C
B.
24 N/C
C.
5 N/C
D.
3 N/C
Correct Answer:
5 N/C
Explanation:
For opposite electric fields, the resultant magnitude is the difference of their magnitudes: E = 8 - 3 = 5 N/C.
3. Two equal electric fields, each of magnitude 5 N/C, act at right angles to each other. What is the magnitude of the resultant field?
A.
5 N/C
B.
10 N/C
C.
25 N/C
D.
approximately 7.1 N/C
Correct Answer:
approximately 7.1 N/C
Explanation:
For perpendicular fields, the resultant is found using the Pythagorean relation: E = √(5² + 5²) = √50 ≈ 7.1 N/C.
4. Electric field E1 is 6 N/C toward the east and electric field E2 is 8 N/C toward the north. What is the magnitude of the resultant electric field?
A.
2 N/C
B.
10 N/C
C.
14 N/C
D.
48 N/C
Correct Answer:
10 N/C
Explanation:
The eastward and northward fields are perpendicular, so the resultant magnitude is E = √(6² + 8²) = 10 N/C.
5. At a point, two electric fields are represented by vectors of 4 N/C toward the east and 4 N/C toward the west. What is the resultant electric field?
A.
8 N/C toward the east
B.
8 N/C toward the west
C.
4 N/C toward the east
D.
0 N/C
Correct Answer:
0 N/C
Explanation:
The two equal electric-field vectors have opposite directions, so they cancel each other and the resultant field is zero.
6. The electric field at a point due to several charges is found by adding their electric-field vectors. Which principle is being used?
A.
Principle of conservation of charge
B.
Principle of superposition
C.
Principle of conservation of energy
D.
Principle of electromagnetic induction
Correct Answer:
Principle of superposition
Explanation:
The superposition principle states that the total electric field is the vector sum of the fields produced by individual charges.
7. Two electric fields of 10 N/C and 6 N/C act in the same direction. What is the resultant field vector?
A.
4 N/C in that direction
B.
16 N/C in that direction
C.
60 N/C in that direction
D.
10 N/C opposite to that direction
Correct Answer:
16 N/C in that direction
Explanation:
Since the two field vectors have the same direction, their magnitudes add: E = 10 + 6 = 16 N/C in the same direction.
8. Two perpendicular electric fields have magnitudes 12 N/C and 5 N/C. What is the magnitude of their resultant?
A.
7 N/C
B.
13 N/C
C.
17 N/C
D.
60 N/C
Correct Answer:
13 N/C
Explanation:
For perpendicular vectors, E = √(12² + 5²) = √169 = 13 N/C.
9. An electric field of 9 N/C acts eastward, while another field of 4 N/C acts westward. What is the direction of the resultant field?
A.
Eastward
B.
Westward
C.
Northward
D.
There is no resultant field
Correct Answer:
Eastward
Explanation:
The eastward field is larger, so after vector subtraction the resultant points eastward, with magnitude 9 - 4 = 5 N/C.
10. If two electric-field vectors at a point have magnitudes 3 N/C and 4 N/C and are perpendicular, which expression gives their resultant magnitude?
A.
3 + 4
B.
4 - 3
C.
√(3² + 4²)
D.
3 × 4
Correct Answer:
√(3² + 4²)
Explanation:
Perpendicular electric-field vectors are added using the Pythagorean theorem, so the resultant is √(3² + 4²) = 5 N/C.