Example 1
Find the value of a resistor with the following code.
1st band → brown
2nd band → black
3rd band → orange
4th band → silver
Solutions
Solutions
BBROYGBVGW
Black = 0, brown = 1, red = 2, orange = 3, yellow = 4, green = 5, blue = 6, violet = 7, grey = 8, white = 9
Tolerance is
Gold ± 5%, silver ± 10%, no band/colour ± 20%
If the colour bands are brown, black and orange
Brown – 1
Black – 0
Orange – 3 ( i.e 3 zeros)
I.e 10 with 3 zeros or 10,000Ω
Question: HOW COME?
Ans: The third band indicate the number of zeros we’ll be having)
10,000Ω resistor with silver forth band, it’s value and tolerance will be 10,000 ohms plus or minus 10%
Question: HOW COME?
And: why is because silver represent 10%)
20% of 10,000 = 10/100 × 10000
= 1000Ω[ohms]Therefore, the resistor will have a value of 10,000 ± 1000
I.e 10,000+1000 or 10,000 – 1000 = 11,000Ω or 9,000Ω. ( 3 marks)
Example 2
Find the value of a resistor with the following color code.
1st band – brown
2nd band – red
3rd band – yellow
4th band – gold
Solutions
Brown = 1, red = 2, yellow = 4 (i.e 4 zeros), gold = 5%
The resistor is 120,000Ω
The resistor value for 120,000Ω of gold 4th band is;
120,000 × 5/100 = 6000Ω
Therefore, the resistor will have a value of 120,000 ± 6000
I.e 120,000 + 6000 = 126,000Ω
120,000 — 6000 = 114,000Ω
= 126,000Ω or 114,000Ω
