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Vectors
Class 12 · Mathematics · 8 questions
Name: ____________________ Date: ____________
The magnitude of the vector 3i + 4j is:
- A 1
- B 5
- C 7
- D 25
The dot product of i and j is:
- A 0
- B 1
- C -1
- D k
If a = (1, 2, 3) and b = (4, 5, 6), then a . b is:
- A 21
- B 6
- C 15
- D 32
i x j equals:
- A 0
- B -k
- C i
- D k
Two vectors are perpendicular when their dot product is:
- A Their product of magnitudes
- B Negative
- C One
- D Zero
The unit vector in the direction of 3i + 4j is:
- A 5i
- B (i + j) / 2
- C (3i + 4j) / 5
- D 3i + 4j
The magnitude of i + j + k is:
- A 0
- B 1
- C The square root of 3
- D 3
The cross product a x b is a vector:
- A Perpendicular to both a and b
- B Parallel to a
- C Parallel to b
- D Of zero length always
Answer key
1. B, 2. A, 3. D, 4. D, 5. D, 6. C, 7. C, 8. A
Square root of (9 + 16) = 5.
Perpendicular unit vectors have dot product 0.
4 + 10 + 18 = 32.
i x j = k.
A . B = A B cos 90 = 0.
Divide by the magnitude 5.
Square root of (1 + 1 + 1).
Its direction follows the right hand rule.