In plywood, three or more veneers in odd numbers are placed one above the other with the direction of grains of successive layers at _____ to each other.
- A45°
- B30°
- C90°Correct
- D60°
Solution
Concept
In plywood, the grain of each veneer is at right angles (90°) to the next veneer. This gives strength in both directions.
Step-by-step solution
1. Plywood is made by gluing thin veneers one above the other. 2. An odd number of veneers (3, 5, 7...) is used so the panel stays balanced. 3. The grain of each layer is placed at right angles to the next layer. 4. So the angle is 90°. Answer is (C).
Explanation
Plywood has an odd number of veneers glued together. The grain of each layer is placed at 90° to the next layer. This cross-grain makes plywood strong in both directions and reduces splitting, shrinkage and warping.
Why the other options are wrong
A, B, D: 45°, 30° and 60° are not used. Only 90° (right angle) gives equal strength in both directions and the least warping.
Shortcut
Plywood = cross-ply = right angle = 90°.
Common mistake
Choosing 45°. Standard plywood always uses 90° between successive layers.
Correct answer: C) 90°