Transistors, Logic Gates and Karnaugh Maps References: Lecture 4 from last.
Grid references on OS maps
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Transcript of Grid references on OS maps
Grid references on OS maps
How to give four figure grid references
A grid reference is a way of giving a position on a map
31 32 33 34 35 36
31 32 33 34 35 36
Grid lines called Eastings are from top to bottom
Grid line numbers are at the top and bottom
So this is Easting 35
Say it as ‘three five’, not as thirty five.
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Grid lines from side to side are called Northings
Grid line numbers are along both sides
So this is Northing 24
Say it as ‘two four’, not twenty four
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31 32 33 34 35 36
31 32 33 34 35 36
What is the four figure grid reference for this square?
A
31 32 33 34 35 36
31 32 33 34 35 36
Find the line along the left of the square.
This is Easting 34
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This is Northing 25
Find the line along the bottom of the square.
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34 The four figure grid reference is 3425
Easting 34
Northing 25Say it as ‘three four two five’
• Find the square
• Look at the line on its left (Easting)
• Find its number from the top or bottom
• Look at the line along its bottom (Northing)
• Find its number from either side
• Write the Easting number, then the Northing number
Remember
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31 32 33 34 35 36
31 32 33 34 35 36
What are the four figure grid references for the squares with these symbols?
3124
3223
3525
3522
3325
All right?
Some wrong?
Double click icons
How to give a
six figure grid
reference
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31 32 33 34 35 36
31 32 33 34 35 36
The church is in square 3224, but where exactly is it?
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31 32 33 34 35 36
31 32 33 34 35 36
It is nearer to 33 than to 32
It is nearer to 24 than to 25
But how ‘near’ is nearer?We need to look more closely.
Look closer at one grid square
320 330
32 33
240 24
250 25
328
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A six figure reference at 328243
Draw lines between the main grid lines
Say it as ‘three two eight, two four three’
• Find the point in the square
• Find the four figure grid reference
• See how far the point is from the line on the left of the square to the line on the right
• See how far the point is from the line along the bottom of the square to the line along the top
Remember
320 330
320 330
240 240
250 250
330248
325243
326247
327240
322246
Where are these symbols?
All right?
Some wrong?
Double click icons
This line first
Then this line
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24
3224
Remember
32
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327
This line first
Then this line
246
Church at 327246
Remember