This set of Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Isometric Axes, Lines and Planes”.

1. The angle between the isometric axes is __________

a) 180 degrees

b) 60 degrees

c) 90 degrees

d) 120 degrees

View Answer

Explanation: Isometric projection is a type of projection in which the three dimensions of a solid are not only shown in one view but also their actual sizes can be measured directly from it. So it is needed that there exist equal angle between the axes for easy measurement so 360/3=120 degrees is chosen.

2. The value of the ratio of isometric length to true length is ________

a) 0.141

b) 0.372

c) 0.815

d) 0.642

View Answer

Explanation: If we represent a cube in isometric view the diagonal of upper face of cube is equal to the true length of the diagonal. From it by drawing an actual square around it and then calculating it gives (1/cos 30)/ (1/cos 45) =isometric /true =0.815.

3. The length in isometric drawing of line is 20 cm. What is the true length of it?

a) 24.53 cm

b) 15.46 cm

c) 19.31 cm

d) 23.09 cm

View Answer

Explanation: The ratio of isometric length to true length is 0.815 so here it is given isometric length of 20 cm. 0.815 = 20 cm / true length => true length = 20 cm /0.815 = 24.53 cm. Every time the true length is more than isometric length.

4. The true length of edge of cube is 15 cm what will be the isometric length?

a) 17.78 cm

b) 14.48 cm

c) 12.99 cm

d) 12.22 cm

View Answer

Explanation: The ratio of isometric length to true length is 0.815 so here it is given true length of 15 cm. 0.815 = isometric length / 15 cm => isometric length = 15 cm x 0.815 = 12.22 cm. Every time the true length is more than isometric length.

5. The lines parallel to isometric axes are called ________ lines.

a) parallel

b) auxiliary

c) isometric

d) oblique

View Answer

Explanation: The angle between the isometric axes is 120 degrees if any line is parallel to it then those are called isometric lines. Auxiliary lines may make any angle with horizontal and oblique is not related here.

6. The planes parallel to any of the two isometric lines are called ________ planes.

a) parallel

b) auxiliary

c) isometric

d) oblique

View Answer

Explanation: The planes on which the faces of cube lie if it is placed in isometric view can be consider as the isometric planes which are parallel to two axes of isometric view which are x, y, z axes of isometric view.

7. Isometric view of cube is drawn the angle between the edge of cube and horizontal will be______

a) 15 degrees

b) 120 degrees

c) 45 degrees

d) 30 degrees

View Answer

Explanation: Isometric view of cube is drawn the angle between the edge of cube and horizontal will be 30 degrees because as the angle between the base and axis lower to will be 90 degrees the angle between the axes is 120 degrees. 120-90 = 60 degrees.

8. Isometric view of cube is drawn the angle between the edge of cube and vertical will be______

a) 15 degrees

b) 120 degrees

c) 60 degrees

d) 30 degrees

View Answer

Explanation: Isometric view of cube is drawn the angle between the edge of cube and vertical will be 60 degrees because the angle between the edge and horizontal is 30 and so angle between vertical and horizontal is 90. 90 – 30 = 60 degrees.

9. The true length of line is 40 cm and isometric view of it is drawn the length would decrease to ______

a) 28.28 cm

b) 32.6 cm

c) 34.6 c

d) 38.63 cm

View Answer

Explanation: The ratio of isometric length to true length is 0.815 so here it is given true length of 40 cm. 0.815 = isometric length / 40 cm => isometric length = 40 cm x 0.815 = 32.6 cm. Every time the true length is more than isometric length.

10. The true length of the line is 30 cm and isometric view is drawn. How much length is reduced?

a) 24.45 cm

b) 25.98 cm

c) 4.01 cm

d) 5.55 cm

View Answer

Explanation: The ratio of isometric length to true length is 0.815 so here it is given true length of 30 cm. 0.815 = isometric length / 30 cm => isometric length = 30 cm x 0.815 = 24.45 cm. 30 cm – 24.45 cm =5.55 cm.

11. The objects we see in nature will be in Isometric view.

a) True

b) False

View Answer

Explanation: The objects we watch in our surrounds are not isometric view they are perspective view. Isometric view is imaginary view in which lines of sight are perpendicular to picture plane and are parallel to each other.

12. Isometric view of cube is drawn the angle between the adjacent edges is _________

a) 90 degrees, 120 degrees

b) 60 degrees, 120 degrees

c) 120 degrees, 120 degrees

d) 90 degrees, 30 degrees

View Answer

Explanation: Given is a cube in which the adjacent angle are all equal and equal to 90 degrees and if isometric view is drawn then it show front faces with angles bet between them as 120 degrees and if take angles between the back and front faces we get the 60 degrees.

13. Isometric view of cube is drawn and faces of cube are seen as ___________

a) square

b) rectangle

c) rhombus

d) parallelogram

View Answer

Explanation: It is given isometric view of cube is drawn and it shows regular hexagon in which any of the faces represent rhombus which have diagonals cutting each other at 90 degrees any other adjacent edges have angles between them as 60 and 120 degrees.

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