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Question-17-8-19 Ans

The document contains 26 multiple choice questions related to vector calculus and multivariable calculus concepts. Some key concepts covered include: finding the magnitude of tangential acceleration of a particle moving along a curve; determining angles in triangles defined by vector relationships; finding directional derivatives and gradients; applying vector calculus theorems like Gauss' divergence theorem and Stokes' theorem; and finding unit vectors parallel and normal to surfaces.

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0% found this document useful (0 votes)
337 views14 pages

Question-17-8-19 Ans

The document contains 26 multiple choice questions related to vector calculus and multivariable calculus concepts. Some key concepts covered include: finding the magnitude of tangential acceleration of a particle moving along a curve; determining angles in triangles defined by vector relationships; finding directional derivatives and gradients; applying vector calculus theorems like Gauss' divergence theorem and Stokes' theorem; and finding unit vectors parallel and normal to surfaces.

Uploaded by

payigiy
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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1. A particle moving along the curve 𝑟⃗ = (𝑡 4 − 4)𝑖̂ + (𝑡 2 + 2)𝑗̂ + (𝑡 − 1)𝑘̂ , where 𝑡 is the time.

Find
the magnetude of the tangential component of its acceleration at 𝑡 = 4 is.
(a) (b) (c) (d)
Ans:
2. Let 𝑎⃗ be a unit vector and 𝑏⃗⃗ be an non-zero vector not parallel to 𝑎⃗. If two sides of the triangle are
represented by the vectors √3(𝑎⃗ × 𝑏⃗⃗) and 𝑏⃗⃗ − (𝑎⃗. 𝑏⃗⃗)𝑎⃗, then the angles of the triangle are
(a) 30°, 90°, 60° (b) 45°, 45°, 90° (c) 60°, 60°, 60° (d) None of these
Ans: (a)
3. The angle between the surface 𝑥² + 𝑦² + 𝑧² = 9 and 𝑥² + 𝑦² − 𝑧 = 10 at (2, −1, 2)is
8 −8 3 −16
(a) cos −1 (3√21) (b) cos −1 (3√21) (c) cos −1 (8√7) (d) cos −1 ( )
√21

Ans:
4. If the surface 5𝑥 2 − 2𝑏𝑦𝑧 − 9𝑥 be orthogonal to the surface 4𝑥 2 𝑦 + 𝑧 3 − 4 at the point (1, −1, 2)
the 𝑏 is equal to 𝑎.
(a) 0 (b) 1 (c) 2 (d) 3
Ans: (b)
5. The direction of grad 𝑄 is
(a) Tangential to level surface (b) Normal to level surface
(c) Inclined at 45° to level surface (d) Arbitrary
6. If 𝑄(𝑥, 𝑦, 𝑧) is a scalar function which satisfies the laplaces equation, then the gradient of 𝜙 is
(a) Slenoidal and irrotational (b) Solenoidal but not irrotational
(c) Irrotation but not Solenoidal (d) Neither Solenoidal nor irrotaitonal
Ans: 9a)
7. A unit vector perpendicular to the plane containing 𝐴⃗ = 𝑖̂ + 𝑗̂ − 2𝑘̂ and 𝐵
⃗⃗ = 2𝑖̂ − 𝑗̂ + 𝑘̂ is
1 1
(a) (−𝑖̂ + 3𝑗̂ − 4𝑘̂) (b) (−𝑖̂ + 3𝑗̂ − 3𝑘̂ )
√26 √19
1 1
(c) (−𝑖̂ + 5𝑗̂ − 3𝑘̂) (d) (−𝑖̂ − 5𝑗̂ − 3𝑘̂ )
√35 √35

Ans: (d)
8. The flux leaving any closed surface per unit volume in a vector field 𝐴⃗ is called.
(a) grad 𝑎⃗ (b) div 𝐴⃗ (c) curl 𝐴⃗ (d) flux 𝐴⃗
Ans: (b)
9. The line integral per unit area along the boundary of small area around a point in vector field 𝐴⃗ is
(a) grad 𝐴⃗ (b) div 𝐴⃗ (c) curl 𝐴⃗ (d) line integral of 𝐴⃗
Ans: (c)
10. The Gauss divergence theorem is
(a) ∬ 𝐴⃗. 𝑑𝑠⃗ = ∭(𝑑𝑖𝑣 𝐴⃗)𝑑𝑣 (b) ∬ 𝐴⃗. 𝑑𝑠⃗ = ∭(𝑔𝑟𝑎𝑑 𝐴⃗)𝑑𝑣
𝑠 𝑣 𝑠 𝑣

(c) ∬ 𝐴⃗. 𝑑𝑠⃗ = ∮ 𝐴⃗. 𝑑𝑟⃗ (d) ∫ 𝐴⃗. 𝑑𝑟⃗ = ∬(𝑐𝑢𝑟𝑙 𝐴⃗)𝑑𝑠
𝑠 𝑐 𝑠

Ans: (a)
11. The stokes theorem is

(a) ∬ 𝐴⃗. 𝑑𝑠⃗ = ∮ 𝐴⃗. 𝑑𝑟⃗ (b) ∬(𝑐𝑢𝑟𝑙 𝐴⃗). 𝑛̂𝑑𝑠 = ∮ 𝐴⃗. 𝑑𝑟⃗
𝑠 𝑐 𝑠 𝑐

(c) ∬ 𝐴⃗. 𝑑𝑠⃗ = ∭(𝑑𝑖𝑣 𝐴⃗)𝑑𝑣 (d) ∬ 𝐴⃗. 𝑑𝑠⃗ = ∭(𝑔𝑟𝑎𝑑 𝐴⃗)𝑑𝑣
𝑠 𝑣 𝑠 𝑣

Ans: (b)
12. The divergence of the function 𝑉 = (𝑟 𝑐ol 𝜃)𝑟̂ + (𝑟 sin 𝜃)𝜃̂ + (𝑟 sin 𝜃 cos 𝜙)𝜙̂ is given by
(a) cos 𝜃 − sin 𝜙 (b) 5 cos 𝜃 − sin 𝜙 (c) cos 𝜃 − 5 sin 𝜙 (d) 5 cos 𝜃 + sin 𝜙
Ans: (b)
𝑑𝑎⃗⃗ ⃗⃗
𝑑𝑏 𝑑
13. If =𝑢
⃗⃗ × 𝑎⃗ and ⃗⃗ × 𝑏⃗⃗ then
=𝑢 (𝑎⃗ × 𝑏⃗⃗) is
𝑑𝑡 𝑑𝑡 𝑑𝑡

⃗⃗ × (𝑎⃗ × 𝑏⃗⃗)
(a) 𝑢 (b) (𝑢 ⃗⃗ × 𝑏⃗⃗)
⃗⃗ × 𝑎⃗)(𝑢 ⃗⃗ × 𝑏⃗⃗
(c) 𝑢 (d) 𝑢
⃗⃗ × 𝑎⃗
Ans: (a)
14. The greatest rate of increase of ϕ is
13
(a) √37 (b) − (c) √−13 (d) √36
3

Ans:
15. ∇2 𝑓(𝑟)is equal to
2 2 2 2
(a) 𝑓 ′ (𝑟) + 𝑓 ′ (𝑟) (b) 𝑓 ′′ (𝑟) + 𝑓 ′ (𝑟) (c) 𝑓 ′′ (𝑟) + (𝑓(𝑟) (d) 𝑓 ′ (𝑟) +
𝑟 𝑟 𝑟 𝑟

Ans: (b)
16. The position vector of a particle at time 𝑡 is 𝑟 = cos(𝑡 − 1) 𝑖̂ + sin(𝑡 − 1)𝑗̂ + 𝑎𝑡²𝑘̂ . If at 𝑡 = 1, the
acceleration of the particle be perpendicular to its position vector, then a is equal to
1 1
(a) 0 (b) 1 (c) 2 (d)
√2

Ans: (d)
17. The projection of a vector 𝐴⃗ = 2𝑖̂ − 3𝑗̂ + 6𝑘̂ on vector 𝐴⃗ = 𝑖̂ − 2𝑗̂ + 2𝑘̂ is
8 8 9 8
(a) 5 (b) 3 (c) 7 (d) 9
Ans: (b)
18. If the vectors 𝐴⃗, 𝐵
⃗⃗ and 𝐶⃗ are coplanar then 𝐵
⃗⃗ + 𝜆𝐶⃗, 𝐶⃗ + 𝜇𝐴⃗, 𝐴⃗ + 𝛾𝐵
⃗⃗ (𝜆, 𝜇, 𝛾 are constants) are
(a) always coplanar (b) coplanar definitely if 𝜆𝜇𝛾 ≠ −1
(c) never coplanar (d) none of these
Ans: (b)
19. The vector is ∇[ln |𝑟⃗|] is
(a) along 𝑟⃗ and increasing with 𝑟. (b) along 𝑟⃗ and decreasing with 𝑟
(c) perpendicular to 𝑟⃗ (d) a constant vector along 𝑟⃗
Ans: (b)
20. A particle travels along a circle with constant angular velocity 𝜔
̅.Its linear velocity has
(a) Zero divergence and zero curl (b) Zero divergence but non-zero curl
(c) non-zero divergence but zero curl (d) non-zero divergence and non-zero curl
Ans: (b)
21. ∫( ∇ ̅). 𝑑s̅ over a closed surface is
̅× A
̅
(a) dependent on A ̅ and the nature of the surface
(b) dependent on A
(c) zero always (d) depends only on the nature of the surface
Ans: (c)
22. Given the condition ∇²𝜙 = 0, the solution of the equation ∇² = 𝑘∇
⃗⃗𝜙. ⃗∇⃗𝜙 is given by
𝑘𝜙2 𝑘𝜙 ln 𝜙 𝑘𝜙 ln 𝜙
(a)  = (b)  = 𝑘𝜙² (c)  = (d)
2 2 2

Ans:
23. Consider the surface corresponding to the equation 4𝑥² + 𝑦² + 𝑧 = 0. A possible unit tangent to
this surface at the point (1, 2, −8) is
1 2 8 8 1 1 1 3 4
(a) 𝑖̂ − 𝑗̂ (b) 9 𝑖̂ − 9 𝑗̂ + 9 𝑘̂ (c) 5 (𝑗̂ − 4𝑘̂ (d) − 𝑖̂ + 𝑗̂ − 𝑘̂
√5 √5 √5 √5 √5

Ans: (a)
24. Which of the following vectors is parallel to the surface 𝑥 2 𝑦 + 2𝑥𝑧 = 4 at the point (2, −1, 3).
(a) −6𝑖̂ − 2𝑗̂ + 5𝑘̂ (b) 6𝑖̂ + 2𝑗̂ + 5𝑘̂ (c) 6𝑖̂ − 2𝑗̂ + 5𝑘̂ (d) 6𝑖̂ + 2𝑗̂ + 5𝑘̂
Ans: (d)
25. Consider the surface defined by 𝑎𝑥² + 𝑏𝑦² + 𝑐𝑧 + 𝑑 = 0 where 𝑎, 𝑏, 𝑐, and 𝑑 are constants. If 𝑛̂1
and 𝑛̂2 are unit normal vectors to the surface at the points (𝑥, 𝑦, 𝑧) = (1, 1, 0)and (0,0,1)
respectively and 𝑛̂ is the unit vector normal to both 𝑛̂1 and 𝑛̂2 , then
𝑏𝑖̂ −𝑎𝑗̂ ̂
2𝑎𝑖̂ +2𝑏𝑗̂ −𝑐𝑘 ̂
𝑎𝑖̂ −𝑏𝑗̂ +𝑐𝑘 −𝑎𝑖̂ +𝑏𝑗̂
(a) (b) (c) (d)
√𝑎²+𝑏² √4𝑎²+4𝑏²+𝑐² √𝑎²+𝑏²+𝑐² √𝑎²+𝑏²
Ans: (a)
𝜋 𝜋
26. In spherical polar co-ordinates 𝑟, 𝜃, 𝜙) the unit vector 𝜃̂ at (10, 4 , 2 ) is
1 1 1
(a) 𝑘̂ (b) (𝑗̂ + 𝑘̂) (c) (−𝑗̂ + 𝑘̂) (d) (𝑗̂ − 𝑘̂)
√2 √2 √2

Ans: (d)
27. What is the equation of the plane which is tangent to the surface 𝑥𝑦𝑧 = 4 at the point (1, 2, 2, )?
(a) 𝑥 + 2𝑦 + 4𝑧 = 12 (b) 4𝑥 + 2𝑦 + 𝑧 = 12
(c) 𝑥 + 4𝑦 + 𝑧 = 0 (d) 2𝑥 + 𝑦 + 𝑧 = 6
Ans: (d)
28. ∮ 𝜙𝑑𝑟 = 0 is equal to

(a) ∫ 𝑑𝑠 × ⃗∇⃗𝜙 (b) ∫ ⃗∇⃗𝜙 × 𝑑s⃗ (c) ∫ ⃗∇⃗𝜙 × 𝑑𝑠 (d) ∫ ⃗∇⃗𝜙 × 𝑑r⃗
𝑠 𝑠 𝑠 𝑠

Ans: (a)
29. Consider a vector 𝐹⃗ = 𝑦𝑖̂ + 𝑧³𝑗̂ − 𝑧𝑦𝑘̂ . Let 𝑐 be circle 𝑥² + 𝑦² = 4 on the plane 𝐸 = 2, oriented
counter-clockwise. the value of contour integral is ..........................
(a) 28𝜋 (b) 4𝜋 (c) −4𝜋 (d) −28 𝜋
Ans: (a)
30. For vectors 𝑎⃗ = 𝑖̂ + 𝑗̂, 𝑏⃗⃗ = 𝑖̂ + 𝑗̂ − 𝑘,
̂ 𝑐⃗ = 𝑖̂ − 𝑗̂. The vector product 𝑎⃗ × (𝑏⃗⃗ × 𝑐⃗) is
(a) in the same direction as 𝑎 (b) in the same direction as 𝑏
(c) in the same direction as 𝑐 (d) None of these
Ans:
31. If 𝐹⃗ is a constant vector and 𝑟⃗ is the position vector, then ⃗∇⃗(𝐹⃗ . 𝑟⃗) would be
⃗⃗. 𝑟⃗)𝐹⃗
(a) (∇ (b) 𝐹⃗ ⃗⃗. 𝐹⃗ )𝑟⃗
(c) (∇ (d) |𝑟⃗|𝐹⃗
Ans: (c)
32. If 𝜙 = 2𝑥²𝑦,  = 𝑥𝑧² − 2𝑦, then ∇(∇𝜙 − ∇) is
(a) 6𝑦𝑧 2𝑖̂ + (6𝑥𝑧 − 12𝑥)𝑗̂ + 12𝑥𝑦𝑧 2𝑘̂ (b) (6𝑦𝑧 2 − 12𝑥) + 6𝑥𝑧 2𝑗̂ + 12𝑥𝑦𝑧𝑘̂
(c) 6𝑦𝑧² − 6𝑧²𝑥𝑗̂ + 6𝑥𝑦𝑘̂ (d) None of these
Ans: (b)
33. If 𝐴⃗ is solenoidal, then ∇ × ∇ × ∇ × 𝐴⃗ is equal to
(a) ∇4 𝐴⃗ (b) ) ∇3 𝐴⃗ (c) ) ∇(∇ × 𝐴⃗) (d) ∇𝐴⃗
Ans: (a)
34. If ) 𝐴⃗ and 𝐵
⃗⃗ are irrotational, then 𝐴⃗ × 𝐵
⃗⃗ is
(a) rotational (b) irrotational (c) solenoidal (d) neither of these
Ans: (c)
35. If a vector 𝑟⃗(+) has a constant direction, then,
𝑑𝑟⃗ 𝑑𝑟⃗ 𝑑𝑟⃗ 𝑑𝑟⃗
(a) 𝑟⃗ × 𝑑𝑡 = 0 (b) 𝑟⃗. 𝑑𝑡 = 0 (c) 𝑑𝑡 = 𝑐⃗, 𝑐⃗ being constant vector (d) 𝑑𝑡 = 0
Ans:
𝑑𝑟⃗
36. If = ⃗⃗
0, then which of the following is true?
𝑑𝑡

(a) The vector 𝑟⃗ is a unit vector (b) The direction of 𝑟⃗ is constant


(c) The magnetude of 𝑟⃗ is constant (d) Such vector 𝑟⃗ does not exist
Ans: (c)
37. The equation of the line passing through the point 𝑎⃗ and partial to the line of the intersection of the
planes 𝑟⃗. 𝑛⃗⃗1 = 𝑝𝑖 and 𝑟⃗. 𝑛⃗⃗ = 𝑝2 is
(a) (𝑟⃗ − 𝑎⃗). (𝑛⃗⃗1 × 𝑛⃗⃗2 ) = 0 (b) (𝑟⃗ − 𝑎⃗). (𝑛⃗⃗1 − 𝑛⃗⃗2 ) = 0
(c) (𝑟⃗ − 𝑎⃗) × (𝑛⃗⃗1 × 𝑛⃗⃗2 ) = 0 (d) (𝑟⃗ − 𝑎⃗) × (𝑛⃗⃗1 − 𝑛⃗⃗2 ) = 0
Ans: (a)
38. Two planes 𝑟⃗. 𝑛⃗⃗1 = 𝑝𝑖 and 𝑟⃗. 𝑛⃗⃗1 = 𝑝2 is parallel if
(a) 𝑛⃗⃗1 = 𝑛⃗⃗2 (b) 𝑛⃗⃗1 = −𝑛⃗⃗2 (c) 𝑛⃗⃗1 = ±𝑛⃗⃗2 (d) 𝑝⃗1 = 𝑝⃗2
Ans: (c)
39. The work done by the force 𝐹⃗ = 4𝑦𝑖̂ − 3𝑥𝑦𝑗̂ + 𝑧²𝑘̂ in moving a particle over the circular path 𝑥² +
𝑦² = 1, 𝑧 = 0 from (1,0,0)to (0, 1, 0) is
(a) 𝜋 + 1 (b) 𝜋 − 1 (c) −𝜋 + 1 (d) −𝜋 − 1
Ans:
40. Let 𝑟⃗ be the distance of a point 𝜌(𝑥, 𝑦, 𝑧) from the origin 0. Then ∇𝑟⃗ is a vector.
(a) Orthogonal to ⃗⃗⃗⃗⃗⃗
𝑂𝜌 (b) Normal to the level surface of 𝑟⃗ at ρ
(c) Normal to the surface of the evaluation generated by 𝑜𝜌
⃗⃗⃗⃗⃗ about 𝑥-axis.
(d) normal to the surface of the evaluation generated by 𝑜𝜌
⃗⃗⃗⃗⃗ about 𝑥-axis
Ans: (b)
41. Let 𝐹⃗ = 𝑥𝑖̂ + 2𝑦𝑗̂ + 3𝑧𝑘̂ = 5 be the surface of the sphere 𝑥² + 𝑦²𝑧² = 1 and 𝑛̂ be the inward
unit normal vector to 𝑒. Then ∬ 𝐹⃗ . 𝑛̂ 𝑑𝑠 is
𝑠

(a) 4𝜋 (b) −4𝜋 (c) 8𝜋 (d) −8𝜋


Ans: (d)
42. Let 𝐶 be the boundary of the region 𝑅 {𝑥, 𝑦} ∈ 𝑅: −1 ≤ 𝑦 ≤ 1, 0 ≤ 𝑥 ≤ 1 − 𝑦² oriented in the
counter clockwise direction. The the value of ∮𝑐 (𝑦𝑑𝑥 − 𝑧𝑥𝑑𝑦) is
4 2 2 4
(a) − (b) 1 − (c) (d)
3 3 3 3

Ans: (d)
2𝑥 2𝑦2 4𝑦
43. The flux of the vector field 𝐹⃗ = (2𝜋𝑥 + ) 𝑖̂ + (2𝜋𝑥𝑦 − ) 𝑗̂ along outward normal, across
𝜋 𝜋
the ellipse 𝑥² + 16𝑦² = 4 is equal to,
(a) 4𝜋² − 2 (b) 2𝜋² − 4 (c) 𝜋² − 2 (d) 2𝜋
Ans: (b)
44. Let 𝐹⃗ = (3 + 2𝑥𝑦)𝑖̂ + (𝑥 2 − 3𝑦 2 )𝑗̂ and let 𝐿 be the curve 𝑟⃗(𝑡) = 𝑒 𝑡 sin 𝑡𝑖̂ + 𝑒 𝑡 cos 𝑡𝑗̂, 0 ≤ 𝑡 ≤ 𝜋,
Then ∫ 𝐹⃗ . 𝑑𝑟⃗ =
𝐿

(a) 𝑒 −3𝜋 + 1 (b) 𝑒 −6𝜋 + 2 (c) 𝑒 6𝜋 + 2 (d) 𝑒 3𝜋 + 1


Ans: (d)
45. The directional derivative of 𝑓(𝑥, 𝑦, 𝑧) = 𝑥𝑦² + 𝑦𝑧³ at the point (2, −1, 1) in the direction of the
vector (𝑖̂ + 2𝑗̂ + 2𝑘̂) is –
11 11 3
(a) − (b) (c) − (d) 13/2
3 3 11

Ans: (a)
46. The work done in a moving particle in the force field 𝐹⃗ = 3𝑥²𝑖̂ + (2𝑥𝑧 − 𝑦)𝑗̂ + 𝑧𝑘̂ along the straight
line from (0, 0, 0) to (2, 1, 3) is –
(a) 16 units (b) 22 units (c) 14 units (d) 42 units
Ans: (a)
47. The value of vector integral ∬ 𝐹⃗ . 𝑟⃗𝑑𝑥 (where 𝐹⃗ = 4𝑥²𝑖̂ + 2𝑦𝑗̂ + 𝑧³𝑘̂ and s is the surface bounded by
the region 𝑥² + 𝑦² = 9, 𝑧 = 0, 𝑧 = 2) is –
4𝜋
(a) 𝜋 (b) (c) 108π (d) 181π
2

Ans:(c)
48. The value of ∫ 𝐴⃗. 𝑑𝑠⃗ over the surface of a hemisphere 𝑥² + 𝑦² + 𝑧² = 𝑅² having its centre at the
origin, where 𝐴⃗ = 𝑖̂𝑦³, is
3𝜋𝑎 5 4𝜋𝑎 5 2𝜋𝑎 5 3𝜋𝑎 3
(a) (b) (c) (d)
5 5 5 5

Ans: (c)
49. The rate of change 𝜙 = 𝑥𝑦 + 𝑦𝑧 + 𝑧𝑥 along the direction of 𝑖̂ + 𝑗̂ + 𝑘̂ at (1, 1, 3) is
(a) √3 (b) 4√3 (c) 2√3 (d) 3 + √3
Ans: (b)
50. Where 𝑟⃗ = 𝑦𝑧²𝑖̂ + (𝑦 2 + sin 𝑥𝑧)𝑗̂ + 𝑦𝑧𝑘̂ and s is the boundary of the region compressed of the
parabolic cylinder 𝑧 = 1 − 𝑦², 𝑧 = 0, 𝑥 = 0, 𝑥 = 4, Then the value of ∫𝑠 𝑟⃗ . 𝑑𝑠⃗ is –
5 13 13 6
(a) 13 (b) (c) (d) 13
6 5

Ans: (c)
NAT
51. The flux of the function 𝐹⃗ = 𝑦²𝑥̂ = (3𝑥𝑦 − 𝑧 2 )𝛿̂ + (4𝑦𝑧)𝑧̂ passing through the surface ABCD
along S is .................. .

Ans: 1.16I
𝑟̂
52. Evaluate the integral J = ∫𝑣 (𝑟 + 𝑧) = 𝛻. (𝑟2 ) 𝑑𝑡 is equal to 𝑛𝜋. then the value of 𝑛 is ........... .
(where 𝑣 is the sphere of radius 𝑅 centered at the origin).
Ans: 8.

53. The value of ∮𝑐 𝐴̅. 𝑑𝑠̅ along a square loop of side 𝐿 in a uniform field 𝐴⃗ is ..............
Ans: 0
54. Consider a cylinder of height ℎ and radius 𝑎 closed at both ends, centered at the origin. Let 𝑟⃗ = 𝑖̂𝑥 +
𝑗̂𝑦 + 𝑧̂ 𝑘 be the position vector and 𝑛̂ a unit normal to the surface. The surface integral ∫𝑠 𝑟⃗. 𝑑𝑠⃗ over
the closed surface at the cylinder is 𝑛𝜋𝑎²ℎ. The value of 𝑛 is ................... .
Ans: 3

55. The volume integral of the function 𝑓(𝑟, 𝜃, 𝜙) = 𝑟² cos 𝜃 over the region (0 ≤ 𝑟 ≤ 2 ∶ 0 ≤ 𝜃 ≤
𝜋
) and 0 ≤ 𝜙 ≤ 2𝑛) is ...................
3

Ans: 15

56. By using 0 Greens' theorem the value of the ∮𝑐 (cos 𝑠 sin 𝑦)𝑑𝑥 + (sin 𝑥 cos 𝑦)𝑑𝑦 where 𝑐 is the circle
𝑥² + 𝑦² = 1 is ................... .
Ans: 0
57. Let 𝑠 be the boundary of the region 𝑥² + 𝑦² = 4, 0 ≤ 𝑧 ≤ 3. Oriented with unit normals pointing
outwards. Consider the vector field 𝐹⃗ = (𝑥 3 + cos 𝑦²)𝑖̂ + 6𝑦𝑧𝑗̂ + (𝑥𝑦 2 𝑧 + cos 𝑥𝑦)𝑘̂ the value of the
following integral ∬ 𝐹̅ . 𝑑𝐴̅ is ..................... .
𝑠

Ans: 90π.
−𝑦𝑖̂ 𝑥𝑖̂
58. The value of 𝜙𝐸⃗⃗. 𝑑𝑟⃗ where 𝐹⃗ = 4𝑥²+4𝑦² + 4𝑥 2+4𝑦² and 𝑐 is the unit circle parameterized in the
counter clockwise direction is ................. .
𝜋
Ans: .
3
59. The value of integral ∮𝑐 𝛼𝑑𝑥 + 𝛽𝑑𝑦; for any artitrary constant 𝛼, 𝛽 and say any close 𝛼 curve e
is ........................ .
Ans: 0
60. Consider a closed triangular contour traversed in counter-clockwise direction as shown in the
figure below.

The value of the integral ∮ 𝐹⃗ . 𝑑𝑠⃗ evaluated along this contour, for a vector field 𝐹⃗ = 𝑦𝑒̂𝑥 − 𝑥𝑒̂𝑦
is .............. . (𝑒̂𝑥 , 𝑒̂𝑦 𝑎𝑛𝑑 𝑒̂𝑧 are unit vectors in cartesian co-ordinate system).
61. A hemispherical shell is placed on the 𝑥𝑦-plane centred at the origin. For a vector field 𝜀 =
(−𝑦𝑒̂ 𝑥 +𝑥𝑒̂ 𝑦 )
2 2
̅×̅
. The value of the integral ∫(∇ E)𝑑s̅ over the hemispherical surface is ........... 𝜋.
𝑥 +𝑦

(𝑑𝑠 is the elementary surface are 𝑒̂𝑥 , 𝑒̂𝑦 𝑎𝑛𝑑 𝑒̂𝑧 are unit vectors in cartesian co-ordinates system)
Ans: 2
62. 𝐶 be the circle 𝑥 2 + 𝑦 2 = 1 taken in the anticlockwise sence. then the value of the integral
∫𝑐 (2𝑥𝑦 3 + 𝑦)𝑑𝑥 + (3𝑥 2 𝑦 2 + 2𝑥)𝑑𝑦 equal to ............................ 𝜋.
Ans: 1.
𝑟⃗
63. The value of 𝑥 for which the divergence of the function 𝐹⃗ = |𝑟⃗|𝑛 , 𝑟⃗ = 𝑥𝑖̂ + 𝑦𝑗̂ + 𝑧𝑘̂, |𝑟⃗| ≠ 0
Vanishes is ......................... .
Ans: 3.
64. The value of 𝑐 for which there exist a twice differentiable vector field 𝐹⃗ with curl 𝑃⃗⃗ = 2𝑥𝑖̂ −
7𝑦𝑗̂ + 𝑐𝑧𝑘̂ is ........................... .
Ans: 5
65. Given that 𝑟 = 2𝑖̂ − 𝑗̂ + 2𝑘̂ when 𝑡 = 2 and 𝑟⃗ = 4𝑖̂ − 2𝑗̂ + 3𝑘̂ when 𝑡 = 3. Now,
2
𝑑𝑟⃗
∫ [𝑟⃗. ] 𝑑𝑡 = ⋯ … … … … … … .
𝑑𝑡
2

Ans: Zero
66. The vector area of the surface of the hemisphere 𝑥² + 𝑦² + 𝑧² = 𝑎² with 𝑧 ≥ 0, is ..................
Ans: 𝜋.
67. A particle moves from a point (3, −4, −2) m to a point (−2, 3, 5)m under the influence of a force
𝐹⃗ = (−2𝑖̂ + 3𝑗̂ + 4𝑘̂ )𝑁. The work done by the force is ............... J.
Ans: 59.
68. A rigid body is rotating with an angular velocity 5 radius per second about an axis pralled to 𝑖̂ −
2𝑗̂ + 2𝑘̂ passing through the point (2𝑖̂ − 3𝑗̂ + 𝑘̂). The velocity of the particle at the point (4𝑖̂ −
2𝑗̂ − 𝑘̂ ) is ....................... .
Ans: 13.44
69. A rigid body is spining with an angular velocity 5 units about an axis parallel to (4𝑗̂ − 3𝑘̂ ) and
passing through the point (𝑖̂ + 2𝑗̂ − 3𝑘̂ ). The velocity of the particle at the point (3𝑖̂ − 2𝑗̂ + 𝑘̂ )
is .......................... units.
Ans: 10.77
70. The magnetic force on a particle of charge 𝑒 moving in a static magnetic field 𝐵 ⃗⃗ with a velocity
⃗⃗ is given by 𝐹⃗𝑚 = 𝑒𝑉̅ × 𝐵̅. The work is done by this force is ................... .
𝑉
Ans: Zero
𝑥
71. For the function 𝜙(𝑥, 𝑦) = 𝑥²+𝑦². The magnitude of the directional derivative along a line making
an angle 30° with the positive 𝑥-axis at 0,2) is .........................
Ans: 0.216
𝑟⃗ 1
⃗⃗𝜙 = 5 and 𝜙(1) = 0 then 𝜙(𝑟) is equal to (1 + 3 ) where 𝛼 is a positive constant. The value
72. If ∇ 𝑟 𝑟
of 𝛼 is .................. .
Ans: 0.33
1
73. ∇2 (𝑟 ) = ⋯ … … … … … … … ….

Ans: Zero
74. If 𝐶 be the boundary of the rectangle (in 𝑥𝑦-plane) defined by 𝑦 = 0, 𝑥 = 𝑎, 𝑦 = 𝑏, 𝑥 = 0. Then
the line integral ∫ 𝐹⃗ . 𝑑𝑠⃗ around 𝐶 is ................ 𝑎 3 ; where 𝐹⃗ = (𝑥 2 + 𝑦 2 )𝑖̂ = 2𝑥𝑦𝑗̂.
𝑐

Ans: 0.67

75. 𝐼 = ∬𝑠 𝐴⃗. 𝑘̂𝑑𝑠 over the entire surface s of the region bounded by the cylinder 𝑥² + 𝑧² = 9, 𝑥 =
0, 𝑦 = 0, 𝑧 = 0 and 𝑦 = 8 if 𝐴⃗ = 6𝑧𝑖̂ + (2𝑥 + 𝑦)𝑗̂ − 𝑥𝑘̂ . The value of the integral is .................... π.
Ans: 18.
MSQ
76. The gradient of scalar field 𝑠(𝑥, 𝑦, 𝑧) has the following characteristics.
(a) line integral at a gradient is path independent (b) closed line integral of gradient is zero
(c) Gradient of s is a measure of the maximum rate of change in the field s.
(d) Gradient of s is a scalar quantity.
Ans: (a), (b), (c)
77. If |𝑟⃗(+)| is a constant, then
(a) 𝑟⃗′(+) is orthogonal to 𝑟⃗(+) for every time
(b) 𝑟⃗′(+) is not orthogonal to 𝑟⃗(+) for every time
(c) 𝑟⃗′(+) is orthogonal to any vector for any time
(d) None of these
Ans: (a)
78. If 𝜙 and  are differential scalar fields, then ∇𝜙 × ∇ is/are
(a) Irrotational (b) Solenoidal (c) Errotational and Solenoidal(d) None of these
Ans: (b)
79. Which statements is/are correct?
III. Green's theorem can be extended to regions bounded by a finite number of simple closed
curves not intersecting one another.
II. Green's theorem can be entended to regions bounded by a infinite number of simple curves
and all are intersecting are another.
𝜕𝜙 𝜕
I. If 𝜙(𝑥, 𝑦),  (𝑥, 𝑦), 𝜕𝑦 , 𝜕𝑥 be continuous functions over a region R bounded by simple closed
curve e in 𝑥 − 𝑦 plane, then,

𝜕 𝜕𝜙
∮ (𝜙 𝑑𝑥 + 𝑑𝑥) = ∬ ( − ) 𝑑𝑥𝑑𝑦
𝜕𝑥 𝜕𝑥
𝑐 𝑅

(a) I and II (b) I and III (c) only I (d) Only II


Ans: (b)
80. Let there be three types of terms 𝐴⃗ × 𝐵
⃗⃗, 𝐴⃗. 𝐵 ⃗⃗ × ⃗⃗⃗⃗⃗
⃗⃗, 𝐴⃗. (𝐵 𝐶) which of the following statements is/are
true?
(a) The first one is a polar vector, the second are a proper scalar and the third a pseudoscalar.
(b) The first one is an axial vector, the second a proper scalar and the third a pseudoscalar.
(c) The first one is an axial vector while the other two are proper scalars.
(d) The first one is an oxial vector while the other two are pseudoscalars.
Ans: (b)
81. Let the vector fields are defined as
𝑥𝑖̂ +𝑦𝑖̂
⃗⃗ = 𝑦𝑖̂+𝑥𝑖̂
𝑃⃗⃗ = 𝑥²+𝑦² and 𝑄 𝑥²+𝑦²

(a) 𝑃⃗⃗ is conservative ⃗⃗ is conservative


(b) 𝑄
(c) 𝑃⃗⃗ is not conservative ⃗⃗ is not conservative
(d) 𝑄
Ans:
82. If 𝑟⃗ = 𝑥𝑖̂ + 𝑦𝑗̂, then,
(a) 𝛻⃗⃗ . 𝑟⃗ = 3 (b) 𝛻⃗⃗ × 𝑟⃗ = 2 (c) 𝛻⃗⃗ . 𝑟⃗ = 2 (d) 𝛻⃗⃗ × 𝑟⃗ = 0
Ans: (a) and (d)
83. A hemispherical shell is placed on the 𝑥𝑦 -plane centred at the origin. For a vector Field 𝐸⃗⃗ =
(−𝑦𝑒̂ 𝑥 +𝑥𝑒̂ 𝑦 )
⃗⃗ × ⃗E⃗). 𝑑s⃗ over the himispherical surface is
. The value of the integral ∫(∇
𝑥 2 +𝑦2
(a) 2 (b) –2 (c) 1 (d) -1
Ans: (a) and (b)
84. A vector field is given by
𝛼 (𝑥𝑖̂ − 𝑦𝑗̂) for 𝑥² + 𝑦² ≤ 𝑟02 (R − I)
𝐹⃗ (𝑟) = { 2 (𝑥𝑖̂−𝑦𝑗̂ )
𝛼𝑟0 (𝑥 2+𝑦2 ) for 𝑥² + 𝑦² ≤ 𝑟02 (R − II)

Here 𝛼 and 𝑟0 are two constants. The curl of this field is


(a) Zero in region II (b) 2𝛼𝑘̂ in region I
(c) 2𝛼𝑘̂ in region II (d) zero in region I
Ans: (a) and (b)
85. ⃗⃗ = 𝑝(𝑥, 𝑦)𝑖̂ + 𝑞(𝑥, 𝑦)𝑗̂ is continuously differentiable vector field defined in a domain D in
Suppose 𝑉
R². Which one of the following statement is NOT equivalent to the remaining ones?
𝜕𝜙 𝜕𝜙
Statement-I: There exists a function 𝜙(𝑥, 𝑦) such that = 𝑝(𝑥, 𝑦) and = 𝑞(𝑥, 𝑦) for all
𝜕𝑥 𝜕𝑦
(𝑥, 𝑦) ∈ 𝐷.
𝜕𝜙 𝜕𝜙
Statement-II : 𝜕𝑥 = holds at all points of D.
𝜕𝑦

⃗⃗ . 𝑑𝑟⃗ = 0 for every piecewise smooth closed curve C in D.


Statement-III: ∮ 𝑉
(a) Statement-I only (b) Statement-II only (c) Statement-I and II (d) None of these
Ans: (b)
86. For the vector field 𝐹⃗ = 𝑦𝑧²𝑖̂ + (𝑥𝑧 2 + 𝑎𝑦𝑧)𝑗̂ + (𝑏𝑥𝑦𝑧 + 𝑥 2 )𝑘̂ . The value of constant 𝑎 and 𝑏 for
which field is conservative are –
(a) The value of constant 𝑎 = 𝑧 (b) The value of constant 𝑏 = 𝑧
(c) The value of constant 𝑎 and 𝑏 are zero
(d) The field is conservative for arbitrary value of 𝑎 and 𝑏.
Ans: (a) and (b)
87. ⃗⃗𝐺 ≠ 0,
Let 𝐺(𝑥, 𝑦) be a function which is continuously differentiable real valued function, with ∇
then,
I. The gradient ⃗∇⃗𝐺 is normal to any level curve
II. The gradient ⃗∇⃗𝐺 is normal to any level curve 𝐺(𝑥, 𝑦) = 𝑐
⃗⃗𝐺).
III. The value of 𝑓(𝑥, 𝑦) increases the fastest in the direction of (∇
(a) Statement-I is correct (b) Statement-II is correct
(c) Statement-III is correct (d) None of the statements are correct
Ans: (b) and (c)
88. Let 𝑟⃗ = 𝑥𝑖̂ + 𝑦𝑗̂ + 𝑧𝑘̂ be the position vector field in region 𝐷. Then |𝑟⃗|2 = 𝑟⃗. 𝑟⃗ = 𝑥² + 𝑦² + 𝑧² is a
real valued function. The value of ∇ ⃗⃗ × (∇
⃗⃗|𝑟⃗|2 ) is

(a) 𝑖̂ + 𝑗̂ + 𝑘̂ (b) 0 (c) 𝑖̂ + 𝑗̂ − 𝑘̂ (d) 𝑖̂ − 𝑗̂ + 𝑘̂


Ans: (b)

89. The divergence theorem is defined as ∫𝑠 𝐹⃗ . 𝑛̂𝑑𝑥 = ∫𝑠 (∇


⃗⃗. 𝐹⃗ )𝑑𝑣. Let 𝐹⃗ = 𝑢(∇
⃗⃗𝑣), then the correct
expressions for the divergence theorem are,

⃗⃗𝑢)( ⃗∇⃗𝑉)𝑑𝑉 = ∬(𝑢∇


Statement − I ∶ ∭ 𝑢∇²𝑉 + (∇ ⃗⃗𝑉)𝑑𝑠
𝑣 𝑠

⃗⃗𝑉 − 𝑉∇
Statement − II: ∭(𝑢 ∇²𝑉 − ∇²𝑉)𝑑𝑉 = ∬(𝑢∇ ⃗⃗𝑢)𝑑𝑠
𝑣 𝑠

(a) Statement I is wrong (b) Statement II is wrong


(c) Statement I is correct (d) Statement II is correct
Ans:
90. 𝑉 is the closed region bounded by the planes 4𝑥 + 2𝑦 + 𝑧 = 8, 𝑥 = 0, 𝑦 = 0 and 𝑧 = 0. The value
of ∫ 𝑥 2 𝑦𝑑𝑉 is
128 38 138 238
(a) (b) 45 (c) (d)
45 45 45

Ans:
91. If 𝐴⃗ is a conservative vector field: and 𝐴⃗ = ∇
⃗⃗𝜙, where 𝜙 is a scalar function of position, then
𝑝

(A) ∫ 𝐴⃗. 𝑑𝑟⃗ is independent of path 𝑄 to 𝑃 (B) ∮ 𝐴⃗. 𝑑𝑟⃗ = ∮ ⃗∇⃗(𝜙). 𝑑𝑟⃗ = ∮ 𝑑𝜙 = 0
𝑄 𝑒 𝑒

(a) (A) is correct (b) B is correct


(c) A and B are not correct (d) None of these
Ans: (a) and (b)
92. If 𝐴⃗ and 𝐵
⃗⃗ are irrotational, then 𝐴⃗ × 𝐵
⃗⃗ is
(a) rotational (b) irrotational (c) solenoidal (d) neither of these
Ans: (c)
93. The vector 𝐹⃗ = 𝑟 𝑛 𝑟⃗ is solenoidal if
⃗⃗. 𝐹⃗ = 0
(a) ∇ (b) 𝑛 = 3 (c) 𝑛 = −3 (d) 𝑛 = 0
Ans: (a) and (c)
⃗⃗
𝜕𝐵
94. If ⃗∇⃗ × 𝐴⃗ = 𝜕𝑡 then ⃗∇⃗. 𝐵
⃗⃗ is /are

(a) independent on time (b)dependent on time


(c) partially dependent on time (d) None of these
Ans: (a)
95. If ⃗∇⃗ × ⃗A⃗ = 0, then ⃗∇⃗ × (A
⃗⃗ × 𝑟⃗) is/are

(a) 0 (b) 3 (c) 2 ⃗⃗ × 𝑟⃗


(d) A
Ans: (a)
96. I. If ∇ ⃗⃗ = 0 then ∇
⃗⃗ × A ⃗⃗ × r⃗) = 0
⃗⃗. (A

II. ⃗⃗ × r⃗) = 2A
⃗∇⃗ × (A ⃗⃗

III. ⃗⃗ × ∇
(A ⃗⃗
⃗⃗) × r⃗ = −2A

(a) expression-I is correct (b) expression-II is correct


(c) expression-III is correct (d) None of these
Ans: (a), (b) and (c)
97. If 𝑛̂ be a unit vector, then
I. ⃗∇⃗. (𝑛̂. r⃗)𝑛̂ = 1

II. ⃗∇⃗ × (𝑛̂. r⃗)𝑛̂ = 0

III. ⃗⃗. [𝑛̂ × r⃗) × 𝑛̂] = 2



IV. ⃗⃗ × [(𝑛̂ × r⃗) × 𝑛̂] = 0

(a) I and II is correct (b) I and II and III is correct
(c) All expression is incorrect (d) All are correct
Ans: (d)
98. If ⃗A⃗ = 𝑥𝑦𝑖̂ + 𝑏𝑦𝑗̂ + 𝑐𝑧𝑘̂ , where 𝑎, 𝑏, 𝑐 are constants, then

⃗⃗ . 𝑛̂𝑑s⃗ where s is the surface of a unit sphere, is


∬A
𝑠
4 4 4
(a) 3 𝜋(𝑎 + 𝑏 + 𝑐) (b) 3 𝜋 2 (𝑎 + 𝑏 + 𝑐) (c) 0 (d) 3 𝜋(𝑎 2 + 𝑏2 + 𝑐 2 )
Ans: (a)

99. A necessary and sufficient condition that the line integral ∫𝑐 𝐴⃗ . 𝑑𝑟⃗ = 0 for every closed curve
𝑐 is that
(a) ⃗∇⃗ × 𝐴⃗ = 0 (b) ⃗∇⃗ × 𝐴⃗ ≠ 0 (c) ⃗∇⃗. 𝐴⃗ ≠ 0 (d) 𝐴⃗ = ⃗∇⃗
Ans: (a) and (b)
100. The area bounded by a simple closed curve, then
1
(a) ∮𝑥 (𝑥𝑑𝑥 − 𝑦𝑑𝑦) (b) ∮𝑐 (𝑥𝑑𝑥 − 𝑦𝑑𝑦) (c) ∮(𝑥𝑑𝑦 − 𝑦𝑑𝑥) (d) ∮𝑐 𝑥𝑦𝑑𝑦𝑑𝑥
2

Ans: (c)

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