Question

The lengthening joints used in timber constructive are : 
• [A.] Cogged joint 
• [B.] Lapped joint 
• [C.] Fished joint 
• [D.] Dove tailed joint 
• [E.] Mitred joint Choose the correct answer from the options given below :

• A. A and D
• B. B and C
• C. C and D
• D. B and E

Hint:

Timber joint applications:
• Lapped joint → lengthening
• Fished joint → strengthening and lengthening
• Dovetail joint → furniture corners
• Mitred joint → frame corners

Answer 1

The Correct Option is B

Concept: Timber joints are used to connect wooden members in construction. Lengthening joints are specifically used to increase the length of timber members by joining two pieces end-to-end. Common lengthening joints include:
• Lapped joints
• Fished joints
• Scarf joints

Step 1: Analyze Cogged joint.
Cogged joints are mainly used for connecting beams and joists at right angles. Hence, statement A is incorrect.

Step 2: Analyze Lapped joint.
Lapped joints are used to join timber pieces for extending length. Hence, statement B is correct.

Step 3: Analyze Fished joint.
Fished joints use side plates (fish plates) to strengthen and lengthen timber members. Hence, statement C is correct.

Step 4: Analyze Dove tailed joint.
Dovetail joints are mainly used in furniture and corner joints. Hence, statement D is incorrect.

Step 5: Analyze Mitred joint.
Mitred joints are corner joints generally used for frames and finishing work. Hence, statement E is incorrect.

Step 6: Choose the correct option.
The lengthening joints are: \[ \text{Lapped joint and Fished joint} \] Therefore, the correct answer is: \[ {\text{(B) B and C}} \]