# Civil Engineering Drawing Questions and Answers – Scales

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This set of Civil Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Scales”.

1. When drawings are drawn smaller than the actual size of the objects the scale used is said to be _________
a) Enlarging scale
b) Reducing scale
c) Small scale
d) Decreasing scale

Explanation: Dimensions of large objects must be reduced to accommodate on standard drawing sheets. It is not any physical instrument but a ratio taken between actual and drawing objects, the drawing is drawn small and this ratio is termed as reducing scale. Don’t get confused as reducing-scale is also used by surveyors for reducing chains and links to acres and roods.

2. The ratio of the length of the drawing of the object to the actual length of the object is called ___________
a) Resulting fraction
b) Representative figure
c) Representative fraction
d) Representative index

Explanation: Representative fractions are a unit-less relation between one “unit” on the map and however many “units” of the same type on the ground. When a 1 cm long line in a drawing sheet represents 1 m length of the actual object on the ground, the R.F is equal to 1 cm/1 m = 1/100. These are of 3 types-full scale, reduced scale and enlarged scale.

3. The scale of chords is used to measure _________
a) Chords
b) Lines
c) Angles
d) Diameter

Explanation: Used to read angle if there is no protractor. To draw an angle, compasses describe an arc from origin with a radius taken from the 60 mark. The required angle is copied from the scale by the compasses, and an arc of this radius drawn from the sixty mark so it intersects the first arc. The line drawn from this point to the origin will be at the target angle.

4. What is the use of circular vernier as a measuring instrument?
a) Measuring small angle
b) Measuring large angle
c) Measuring required accurate angle
d) Normal angle

Explanation: Verniers are also extensively used to circular scales in variety of scientific instruments.
The below figure shows typical arrangement of double direct verniers.

In Fig. the scale is graduated to 10 and value of n=10 on the vernier. 10 vernier divisions = 9 main scale divisions. Hence the least count is = d/n = 10/10 = 6′. The reading is 19 0 48′.

5. If the measurement required is in three units, which scale would you prefer?
a) Plain
b) Comparative
c) Diagonal
d) Vernier

Explanation: Diagonal scales are used when very minute distances such as 0.1 mm etc. are to be accurately measured or when measurements are required in three units; example- dm, cm and mm, or yard, foot and inch. While other options only give measurement in single unit.
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6. Vernier scale consists of two important parts, vernier scale and _________
a) Secondary scale
b) Initial scale
c) Main scale
d) Large scale

Explanation: The scale on the larger, fixed portion of the calliper. It gives the most significant digits in the reading, while the vernier is the sliding portion giving the least significant digits in the reading. It can be further divided into sub-parts as internal jaws, external jaws, locking screw etc.

7. A room of 1728 m3 volume is shown as 216 cm3 volume on a drawing sheet. What is the R.F?
a) 1/20
b) 1/200
c) 1/250
d) 1/186

Explanation: Since volume is given, formula will turn as
R.F = (drawing volume/original volume)3
R.F = (216 cm3 / 1728 * (100)3 cm3)3
= 1/200.

8. The area of field is 25,000m2. Length and breadth of the field, on the map is 5cm and 5cm respectively. What is the Representative Fraction of the scale?
a) 1/1200
b) 1/3100
c) 1/3162
d) 1/3200

Explanation: Area of the field = 25,000m2
Area of field on the map = 5cm*5cm = 25cm2
1cm2 = 25000/25 = 1000m2
1 cm = 31.62 m
Now Representative Fraction = 1cm /31.62m = 1/3162.

9. One furlong = ________ meters.
a) 180
b) 300
c) 100
d) 200

Explanation: The furlong was the distance a team of oxen could plough without resting. This was standardized to be exactly 40 rods (1 rod = 51/2 yards) or one-eighth of a mile or 660 feet given by U.S unit system. Accurately one furlong = 201.168 meters.

10. Length of scale (LOS) = ______ × ______
a) Max. Length and R.F
b) R.F and Min. length
c) R.I and Max. Length
d) E.I and Max. Length

Explanation: Representative fraction (R.F.) = (Length of object on the drawing)/(Actual length of the object). If the R.F is known and the maximum length of the actual area is given, then we can find the length of scale and after which the drawing is executed below the max. length of scale. It is calculated by the following formula: Length of scale = (RF x Maximum distance to be represented).

11. What is the scale ratio of full size scales?
a) 1:2
b) 1:3
c) 1:10
d) 1:1

Explanation: As the name suggests it does not make any changes in the scale, no increment or decrement to the figure is done. The dimensions for drawing will be full, same in proportion and size as the actual object dimensions.

12. For a plain scale, RF = $$\frac{1}{4}$$ and M.L = 5decimeters, what is LOS?
a) 1.25 cm
b) 12.5 cm
c) 12.5 m
d) 12.5dm

Explanation: LOS = R.F*M.L = $$\frac{1}{4}$$*5 *10 cm (Since 1dm = 10 cm)
= 12.5 cm.

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