Quick Review Flashcards - Click to flip and test your knowledge!
Question
Define 'Map Scale' in the context of geographic representation.
Answer
The proportion that the distance between any two points on a map bears to the distance between the same two points on the surface of the earth.
Question
What is the mathematical formula used to express Scale?
Answer
$Scale = \frac{\text{Map distance between two points}}{\text{Ground distance between the same points}}$
Question
Name the three main methods used to represent scale on a map.
Answer
(i) A Statement, (ii) Linear or Graphic Scale, and (iii) Representative Fraction (R.F.).
Question
In a 'Statement' scale, which side of the statement usually represents the map distance?
Answer
The value on the left-hand side.
Question
Why is the Statement method of scale representation considered unsuitable for international use?
Answer
It requires the user to know the specific units of measurement used in the country of the map's origin.
Question
What happens to the scale of a map if the original document is reduced or enlarged?
Answer
The scale does not remain the same, creating problems in measurement.
Question
Term: Linear (or Graphic) Scale
Answer
Definition: A scale represented by a straight line divided into equal parts to show what markings represent on the actual ground.
Question
On a linear scale, what are the major divisions called?
Answer
Primary Divisions.
Question
On a linear scale, what are the smaller units graduated from right to left on one primary division called?
Answer
Secondary Divisions.
Question
In which direction are the Primary Divisions on a linear scale typically graduated?
Answer
From left to right.
Question
Term: Representative Fraction (R.F.)
Answer
Definition: A scale represented as the ratio of map line length to corresponding actual ground distance, where the numerator is always unity.
Question
What must be true about the units of measurement for the numerator and denominator in a Representative Fraction?
Answer
They must be the same unit of measurement.
Question
What is the formula for calculating Representative Fraction (R.F.)?
Answer
$R.F. = \frac{\text{Distance on the map}}{\text{Distance on the ground in the same unit}}$
Question
Why is the Representative Fraction also known as the 'International Scale' or 'Natural Scale'?
Answer
It is independent of any particular unit of measurement and has universal application.
Question
How many centimetres are in $1\text{ kilometre}$ for the purposes of scale conversion?
Answer
$100,000\text{ cm}$.
Question
How many inches are equivalent to $1\text{ mile}$?
Answer
$63,360\text{ inches}$.
Question
Calculate the R.F. if a distance of $50\text{ km}$ is represented by a line of $5\text{ cm}$ on a map.
Answer
$1:1,000,000$.
Question
What is the R.F. of a scale stated as $1\text{ inch to }4\text{ miles}$?
Answer
$1:253,440$.
Question
Why is the graphical method (linear scale) preferred over R.F. or verbal statements when resizing maps?
Answer
It remains valid and accurate even if the map is reduced or enlarged.
Question
Which simple tool, consisting of two pointed legs, can be used to measure straight distances on a map?
Answer
A divider.
Question
Describe the 'Thread' method for measuring distances along curves.
Answer
A thread is laid along the curved course (e.g., a river), then straightened and measured against the linear scale.
Question
Term: Opisometer
Answer
Definition: An instrument with a small spiked wheel used to measure curved distances on a map by recording revolutions on a dial.
Question
On a map where the scale is $2\text{ cm} = 1\text{ km}$, what is the area of a single $2\text{ cm} \times 2\text{ cm}$ grid square?
Answer
$1\text{ sq. km}$.
Question
In the Grid Square Method for area calculation, how are squares covering more than half the area counted?
Answer
They are counted as $\frac{2}{3}$ squares.
Question
In the Grid Square Method for area calculation, how are squares covering less than half the area counted?
Answer
They are counted as $\frac{1}{3}$ squares.
Question
In the Grid Square Method for area calculation, how are squares covering exactly half the area counted?
Answer
They are counted as $\frac{1}{2}$ squares.
Question
What are the four 'Cardinal Points' used for direction on a map?
Answer
North, South, East, and West.
Question
Identify the cardinal point located exactly between North and East.
Answer
North-East (NE).
Question
Identify the cardinal point located exactly between South and West.
Answer
South-West (SW).
Question
Identify the cardinal point located exactly between North and West.
Answer
North-West (NW).
Question
Identify the cardinal point located exactly between South and East.
Answer
South-East (SE).
Question
Term: Bearing
Answer
Definition: The horizontal angle between the North and the line joining the observer to an object, measured in a clockwise direction.
Question
What is the 'Forward Bearing' (FB)?
Answer
The bearing measured from the observer's position to the target object.
Question
What is the 'Backward Bearing' (BB)?
Answer
The bearing measured from the target object back to the observer's position.
Question
What is the formula for calculating Backward Bearing if the Forward Bearing is less than $180^{\circ}$?
Answer
$BB = FB + 180^{\circ}$.
Question
What is the formula for calculating Backward Bearing if the Forward Bearing is greater than $180^{\circ}$?
Answer
$BB = FB - 180^{\circ}$.
Question
What is the numerical bearing in degrees for an object pointing exactly East?
Answer
$90^{\circ}$.
Question
What is the numerical bearing in degrees for an object pointing North-East?
Answer
$45^{\circ}$.
Question
Term: True Bearing
Answer
Definition: A bearing measured with reference to the geographic (true) north-south line.
Question
Term: Magnetic Bearing
Answer
Definition: A bearing measured with reference to the magnetic north-south line.
Question
What instrument is used to determine 'Magnetic North'?
Answer
A Magnetic Compass.
Question
How is 'True North' (Geographic North) defined in relation to celestial bodies?
Answer
It is the direction indicated by the North Star.
Question
Term: Magnetic Declination
Answer
Definition: The angular difference between the true north-south line and the magnetic north-south line.
Question
Why is 'Magnetic North' described as a non-fixed point?
Answer
It moves slowly from time to time, causing variations in magnetic declination.
Question
Term: Isotonic lines
Answer
Definition: Lines on a map that join points sharing similar magnetic variations.
Question
Term: Grid North
Answer
Definition: The North represented on maps by assuming meridians of longitude are straight, vertical lines.
Question
Term: Grid Variation
Answer
Definition: The angular difference between Grid North and True North due to the earth's spherical shape.
Question
If the magnetic variation is $15^{\circ}$ West and the magnetic bearing is $125^{\circ}$, what is the true bearing?
Answer
$110^{\circ}$.
Question
Convert the Representative Fraction $1:500,000$ into a verbal statement using kilometres.
Answer
$1\text{ cm to }5\text{ km}$.
Question
On a linear scale, where are the 'Secondary Divisions' located relative to the zero mark?
Answer
To the left of the zero mark.
Question
What is the bearing of an object pointing South-West?
Answer
$225^{\circ}$.
Question
What is the bearing of an object pointing North-West?
Answer
$315^{\circ}$.
Question
What is the bearing of an object pointing South-East?
Answer
$135^{\circ}$.
Question
In an R.F. of $1:1,000,000$, what ground distance does $1\text{ centimetre}$ on the map represent?
Answer
$1,000,000\text{ centimetres}$ (or $10\text{ km}$).
Question
Why is the numerator in a Representative Fraction always expressed as unity ($1$)?
Answer
To simplify the ratio so that one unit of map distance directly correlates to a specific number of the same units on the ground.
Question
Identify the cardinal point defined by any line at right angles to the north-south line pointing to the right.
Answer
East.
Question
How does the rotation of the Earth define the North and South Poles?
Answer
The northern end of the axis of rotation is the North Pole and the southern end is the South Pole.
Question
What is the result of adding all complete and fractional grid squares in the Grid Square Method?
Answer
The total estimated area of the portion required.
Question
What is the R.F. for a scale where $1\text{ cm} = 1\text{ km}$?
Answer
$1:100,000$.
Question
What is the R.F. for a scale where $5\text{ cm} = 500\text{ metres}$?
Answer
$1:10,000$.