Dot & Cross Product - Electromagnetic
Theory Questions and Answers - Sanfoundry
by staff10
This set of Electromagnetic Theory Multiple Choice Questions & Answers (MCQs) focuses on
“Dot and Cross Product”.
1. When two vectors are perpendicular, their
a) Dot product is zero
b) Cross product is zero
c) Both are zero
d) Both are not necessarily zero
View Answer
Answer: a
Explanation: Dot product of two perpendicular vectors is given by A.B = |a||b|cos 90, which is
zero. Thus, dot product is zero and vectors are perpendicular.
2. The cross product of the vectors 3i + 4j – 5k and –i + j – 2k is,
a) 3i – 11j + 7k
b) -3i + 11j + 7k
c) -3i – 11j – 7k
d) -3i + 11j – 7k
View Answer
Answer: b
Explanation: Cross product of two vectors is, A X B = (a2*b3 – b2*a3)i – (a1*b3 – b1*a3)j +
(a1*b2 – b1*a2)k. Using the formula, the answer can be calculated.
3. Which of the following are not vector functions in Electromagnetics?
a) Gradient
b) Divergence
c) Curl
d) There is no non- vector functions in Electromagnetics
View Answer
Answer: d
Explanation: Since all the coordinates in electromagnetic are space coordinates, direction and
magnitude both are important. Thus all functions are vector only.
4. The work done of vectors force F and distance d, separated by angle θ can be calculated using,
a) Cross product
b) Dot product
, c) Addition of two vectors
d) Cannot be calculated
View Answer
Answer: b
Explanation: Force is a vector quantity, whereas distance is scalar. Work is defined as the
product of force and distance, which is given by dot product.
5. Find whether the vectors are parallel, (-2,1,-1) and (0,3,1)
a) Parallel
b) Collinearly parallel
c) Not parallel
d) Data insufficient
View Answer
Answer: c
Explanation: Two vectors are parallel when their cross product is zero. Since their cross product
is 4i + 2j – 6k (non-zero), the vectors are not parallel.
6. Lorentz force is based on,
a) Dot product
b) Cross product
c) Both dot and cross product
d) Independent of both
View Answer
Answer: b
Explanation: Lorentz force is given by, F = q (v x B).Thus cross product is the answer.
7. Electromagnetic forces are defined by
a) Fleming’s right hand rule
b) Fleming’s left hand rule
c) Faraday’s law
d) Ampere law
View Answer
Answer: b
Explanation: The three left hand fingers denote electric field, magnetic field and wave
propagation in free space, analogous to force, magnetic field and current respectively in any
conductor.
8. The dot product of two vectors is a scalar. The cross product of two vectors is a vector. State
True/False.
a) True
b) False
View Answer
Theory Questions and Answers - Sanfoundry
by staff10
This set of Electromagnetic Theory Multiple Choice Questions & Answers (MCQs) focuses on
“Dot and Cross Product”.
1. When two vectors are perpendicular, their
a) Dot product is zero
b) Cross product is zero
c) Both are zero
d) Both are not necessarily zero
View Answer
Answer: a
Explanation: Dot product of two perpendicular vectors is given by A.B = |a||b|cos 90, which is
zero. Thus, dot product is zero and vectors are perpendicular.
2. The cross product of the vectors 3i + 4j – 5k and –i + j – 2k is,
a) 3i – 11j + 7k
b) -3i + 11j + 7k
c) -3i – 11j – 7k
d) -3i + 11j – 7k
View Answer
Answer: b
Explanation: Cross product of two vectors is, A X B = (a2*b3 – b2*a3)i – (a1*b3 – b1*a3)j +
(a1*b2 – b1*a2)k. Using the formula, the answer can be calculated.
3. Which of the following are not vector functions in Electromagnetics?
a) Gradient
b) Divergence
c) Curl
d) There is no non- vector functions in Electromagnetics
View Answer
Answer: d
Explanation: Since all the coordinates in electromagnetic are space coordinates, direction and
magnitude both are important. Thus all functions are vector only.
4. The work done of vectors force F and distance d, separated by angle θ can be calculated using,
a) Cross product
b) Dot product
, c) Addition of two vectors
d) Cannot be calculated
View Answer
Answer: b
Explanation: Force is a vector quantity, whereas distance is scalar. Work is defined as the
product of force and distance, which is given by dot product.
5. Find whether the vectors are parallel, (-2,1,-1) and (0,3,1)
a) Parallel
b) Collinearly parallel
c) Not parallel
d) Data insufficient
View Answer
Answer: c
Explanation: Two vectors are parallel when their cross product is zero. Since their cross product
is 4i + 2j – 6k (non-zero), the vectors are not parallel.
6. Lorentz force is based on,
a) Dot product
b) Cross product
c) Both dot and cross product
d) Independent of both
View Answer
Answer: b
Explanation: Lorentz force is given by, F = q (v x B).Thus cross product is the answer.
7. Electromagnetic forces are defined by
a) Fleming’s right hand rule
b) Fleming’s left hand rule
c) Faraday’s law
d) Ampere law
View Answer
Answer: b
Explanation: The three left hand fingers denote electric field, magnetic field and wave
propagation in free space, analogous to force, magnetic field and current respectively in any
conductor.
8. The dot product of two vectors is a scalar. The cross product of two vectors is a vector. State
True/False.
a) True
b) False
View Answer
