# Engineering Drawing Questions and Answers – Basics of Orthographic Projections

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This set of Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Basics of Orthographic Projections”.

1. The straight lines which are drawn from various points on the contour of an object to meet a plane are called as _________
a) connecting lines
b) projectors
c) perpendicular lines
d) hidden lines.

Explanation: The object will generally kept at a distance from planes so to represent the shape in that view projectors are drawn perpendicular to plane in orthographic projection. Projectors are simply called lines of sights when an observer looks towards an object from infinity.

2. When the projectors are parallel to each other and also perpendicular to the plane, the projection is called ___________________________
a) Perspective projection
b) Oblique projection
c) Isometric projection
d) Orthographic projection

Explanation: In orthographic projection, the projectors are parallel to each other and also perpendicular to the plane but in oblique projection, the projectors are inclined to the plane of projection and projectors are parallel to each other.

3. In the Oblique projection an object is represented by how many views?
a) one view
b) two views
c) three views
d) four views

Explanation: Oblique projection is one method of pictorial projection. Oblique projection shows three dimensional objects on the projection plane in one view only. This type of drawing is useful for making an assembly of an object and provides directly a production drawing.
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4. The object we see in our surrounding usually without drawing came under which projection?
a) Perspective projection
b) Oblique projection
c) Isometric projection
d) Orthographic projection

Explanation: Perspective projection gives the view of an object on a plane surface, called the picture plane, as it would appear to the eye when viewed from a fixed position. It may also be defined as the figure formed on the projection plane when visual rays from the eye to the object cut the plane.

5. In orthographic projection, each projection view represents how many dimensions of an object?
a) 1
b) 2
c) 3
d) 0

Explanation: In orthographic projection and oblique projection the projection planes which represent one view of an object only shows width, height; width, thickness; height, thickness only but in isometric and perspective projections width, height and thickness can also be viewed.
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6. In orthographic projection an object is represented by two or three views on different planes which _________________
a) gives views from different angles from different directions
b) are mutually perpendicular projection planes
c) are parallel along one direction but at different cross-section
d) are obtained by taking prints from 2 or 3 sides of object

Explanation: By viewing in mutual perpendicular planes- Vertical plane, horizontal plane, profile plane which indirectly gives us front view in x-direction, top-view in y –direction and thickness in z-direction which are mutually perpendicular. Ortho means perpendicular.

7. To represent the object on paper by orthographic projection the horizontal plane (H.P) should be placed in which way?
a) The H.P is turned in a clockwise direction up to 90 degrees
b) The H.P is turned in anti-clockwise direction up to 90 degrees
c) H.P plane is placed to left side of vertical plane parallel to it
d) H.P plane is placed to right side of vertical plane parallel to it

Explanation: The vertical plane and horizontal plane are perpendicular planes intersected at reference line. So on paper to represent perpendicular planes any of the planes should arrange to get a real picture of required projection.

8. The hidden parts inside or back side of object while represented in orthographic projection are represented by which line?
a) Continuous thick line
b) Continuous thin line
c) Dashed thin line
d) Long-break line

Explanation: Continuous thick line is used for visible outlines, visible edges, crests of screw threads, limits of full depth thread etc. Continuous thin line is used for extension, projection, short centre, leader, reference lines, imaginary lines of intersection etc.

9. Orthographic projection is the representation of two or more views on the mutual perpendicular projection planes.
a) True
b) False

Explanation: Orthographic projection is the representation of two or more views on the mutual perpendicular projection planes. But for oblique projection, the object is viewed in only one view. And in isometric view the object is kept resting on the ground on one of its corners with a solid diagonal perpendicular to the V.P.

10. In perspective projection and oblique projection, the projectors are not parallel to each other.
a) True
b) False

Explanation: In Oblique projection the projectors are parallel to each other but inclined to projection plane but in perspective projection all the projectors are not parallel to each other and so to projection plane.

11. What is additional 3rd view on orthographic projection in general for simple objects?
a) Front view
b) Top view
c) Side view
d) View at 45 degrees perpendicular to horizontal plane

Explanation: In general for simple objects engineers use only front view and top view or else front view and side view or else top view and side view. If every view is visualized side view gives height and thickness of object.

12. The front view of an object is shown on which plane?
a) Profile plane
b) Vertical plane
c) Horizontal plane
d) Parallel plane

Explanation: The front view will be represented on vertical plane, top view will be represented on horizontal plane and side view will be shown on profile plane. The front view shows height and width of object.

13. The Top view of an object is shown on which plane?
a) Profile plane
b) Vertical plane
c) Horizontal plane
d) Parallel plane

Explanation: The front view will be shown on vertical plane, top view will be represented on horizontal plane and side view will be represents on profile plane. The top view gives thickness and width of the object.

14. The side view of an object is shown on which plane?
a) Profile plane
b) Vertical plane
c) Horizontal plane
d) Parallel plane

Explanation: The front view will be represents on vertical plane, top view will be shown on horizontal plane and side view will be represents on profile plane. The side view gives height and thickness of object.

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