Representative Fraction and Scale with types.pptx

Representative Fraction and Scale with types

1. REPRESENTATIVE FRACTION, FULL SCALE, REDUCED SCALE & ENLARGED SCALE

2. Question: Define Representative Fraction. Explain Full Scale, Reduced Scale and Enlarged Scale with example. Answer: Representative Fraction is the ratio of size of object in paper to actual size of object. Representative Fraction (R.F.) = Size of object in paper Actual size of object On the basis of above mentioned formula we can explain full scale, reduced scale and enlarged scale.

3. Full Scale: Representative Fraction (R.F.) = 20mm = 1 = 1:1 20mm 1 Here, size of object in paper and actual size of object is same. Use: It is used in general purpose drawing. Representative Fraction (R.F.) = Size of object in paper Actual size of object Draw 20mm size square. Scale 1:1 20 20

4. Reduced Scale : Representative Fraction (R.F.) = 10mm = 1 = 1:2 20mm 2 Here, size of object in paper is less than actual size of object. Use: When size of object is too large. Example: Building drawing, Machinery drawing, map etc. Representative Fraction (R.F.) = Size of object in paper Actual size of object Draw 20mm size square. Other Example: 1:5, 1:10, 1:20, 1:50, 1:100, 1:1000, 1:100000 Scale 1:2 2 2

5. Enlarged Scale : Representative Fraction (R.F.) = 40mm = 2 = 2:1 20mm 1 Here, size of object in paper is greater than actual size of object . Use: When size of object is too small. Example: Parts of wrist watch, parts of electronic circuit etc. Representative Fraction (R.F.) = Size of object in paper Actual size of object Draw 20mm size square. Other Example: 5:1, 10:1, 20:1, 50:1 etc. Scale 2:1 20 20