This set of Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Third Angle Projection Method”.
1. In 3rd angle projection the object is kept in _________
a) 1st quadrant
b) 2nd quadrant
c) 3rd quadrant
d) 4th quadrant
View Answer
Explanation: We can keep object in any quadrant of projection planes but every time we keep in different quadrants gives different relative positions in projections. Here 3rd angle represents the initial stage in forming projection of planes so 3rd quadrant represents 3rd angle projection.
2. 3rd angle projection is recommended by _____________
a) USA
b) ISI
c) Bureau of Indian Standards
d) IS
View Answer
Explanation: Third angle projection is recommended by USA and other countries and 1st angle projection is recommended by Bureau of Indian Standards. The changes in both the projections are relative positions in projection.
3. In 3rd angle projection the _________ lies between ___________ and ____________
a) object, projection plane, observer
b) projection plane, object, observer
c) reference line, side view, front view
d) reference line, left side view, right side view
View Answer
Explanation: The observer is always at the right side top end. So as the observer watches the projection plane comes first and then the object as the object in the 3rd quadrant in 3rd angle projection, so plane of projection lies between object and observer.
4. In 3rd angle projection, the front view will be below the top view.
a) True
b) False
View Answer
Explanation: As the object is in third quadrant and the front view projects on a vertical plane and top view projects on horizontal plane. And for representing the projection the horizontal plane has to turn 90 degrees in clockwise direction. The top view will be above the front view.
5. In 3rd angle projection, the positions of front view and top views are?
a) Top view lies above the front view
b) Front view lies above the top view
c) Front view lie left side to top view
d) Top view lie left side to front view
View Answer
Explanation: As the object is in third quadrant and the front view projects on a vertical plane and top view projects on horizontal plane. And for representing the projection the horizontal plane has to turn 90 degrees in clockwise direction.
6. In 3rd angle projection, the left side view will be left side of front view.
a) True
b) False
View Answer
Explanation: In third angle projection the object’s left side will be projected only if we watch from right side of the object so impression will fall to the left side of front view since the plane of projection is back side of object and also the right side view is placed on the right side of front view.
7. The positions of right side view and front view of an object kept in 3rd quadrant and projection are drawn?
a) right side view is right side of front view
b) right side view is left side of front view
c) right side view is above the front view
d) right side view is below the front view
View Answer
Explanation: In third angle projection the object’s right side will be projected only if we watch from left side of the object and the impression will fall to the right side of front view similar to the other side also so the left side view is placed on the left side of front view.
8. The positions of reference line and top view in 3rd angle projection are?
a) reference line lies above the top view
b) reference line lies below the top view
c) reference line lie left side to top view
d) reference line lie right side to top view
View Answer
Explanation: Reference line will be the xy line which is formed by an intersection of vertical plane and horizontal plane. In the third angle projection the projections of object are taken by placing object in 3rd quadrant and top view is projected on to horizontal plane which is above the reference line.
9. If an object is placed in 3rd quadrant such that one of the surfaces of object is coinciding with vertical plane, what is the correct position of views from the following?
a) The front view touches the reference line
b) The side view touches the reference line
c) The top view touches the reference line
d) The bottom view touches the reference line
View Answer
Explanation: In the third angle projection the projections of object is taken by placing object in 3rd quadrant. If the object’s surface is coinciding the vertical plane which indirectly saying the distance from vertical plane is zero so top view of that object touches the reference line.
10. If an object is placed in 3rd quadrant such that one of the surfaces of object is coinciding with horizontal plane, what is the correct position of views from the following?
a) The front view touches the reference line
b) The side view touches the reference line
c) The top view touches the reference line
d) The bottom view touches the reference line
View Answer
Explanation: In the third angle projection the projections of object is taken by placing object in 3rd quadrant. If the object’s surface is coinciding the horizontal plane which indirectly saying the distance from horizontal plane is zero so front view of that object touches the reference line.
11. If an object is placed in 3rd quadrant such that one of the surfaces of object is coinciding with both vertical plane and horizontal plane, what is the correct position of views from the following?
a) The top view touches the reference line
b) The top view and side view touch each other
c) Both side views touch each other
d) The top view and front touches each other at reference line
View Answer
Explanation: If the object is placed in 3rd quadrant and the object’s surface is coinciding with both the horizontal plane and vertical plane which indirectly saying the distance from both the planes is zero so both top and front views of that object touches the reference line.
12. Where is the position of bottom view in 3rd angle projection?
a) left side of right hand side view
b) right side of right hand side view
c) above the front view
d) below the top view
View Answer
Explanation: Third angle projection means the object is placed in third quadrant and the top view of the object is above the front view so the bottom view is below the front view. This is obtained as the top view is placed above so bottom should be placed below.
13. Where is the position of back view in 3rd angle projection?
a) left side of right hand side view
b) right side of right hand side view
c) above the front view
d) below the top view
View Answer
Explanation: In the third angle projection the top view of the object is above the front view and then come the side views to the left and right of front view and then back view which can either be kept on ends of side views but as standard notation it is placed on right side of right side view.
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