We know, V = IR from ohm's law
Then, R = V/I
Ex.
If the voltage is 5 volt, and the current is 0.5 amps then what is the resistance across this source?
Ans. Hear we know the value of voltage and current. so we apply the ohms low, R = V/I = 5/0.5 = 10 ohm(Ω).
[[Theoretically we can measure the value of resistance in presence of voltage and current. But we can find the value of any resistor through the color coding of this resistor, without any multi-meter.]]
Hear we numbering some colors.
0 = Black, 1 = Brown, 2= Red, 3 = Orange, 4 = Yellow, 5 = Green, 6 = Blue, 7 = Violet, 8 = Gray, 9 = White.
Hear we have a very easy trick to remember those color numbering. that is ""B B ROY Great Britain Very Good Wife.""
1st B = Black = 0
2nd B = Brown = 1
R = Red = 2
O = Orange = 3
Y = Yellow = 4
Great = Green = 5
Britain = Blue = 6
Very = Violet = 7
Good = Gray = 8
Wife = White = 9
Their have two many colors. Such are Gold and Silver.
Golden = ±5% tolerance
Silver = ±10% tolerance
No color = ±20% tolerance
In this above fig. we take the color strips from left side. So, the 1st color is Brown, then Black, Black and Golden.
At first we take the 1st two strips and takes it's number.
Hear Brown = 1 and Black = 0, so, 10.
Then, the 3rd stripe, hear we get the '0' from this color numbering, that means
0 = Black = nothing
1 = Brown = 0
2= Red = 00
3 = Orange = 000
4 = Yellow = 0000
5 = Green = 00000
6 = Blue = 000000
7 = Violet = 0000000
8 = Gray = 00000000
9 = White = 00000000
10 = Golden = 1/10
11 = Silver = 1/100
Simply we add those '0' after 1st and 2nd conditions.
So, in our case we don't use any 0 to this number.
The 4th strip is golden in color, so, it indicates ±5% tolerance.
So, the net result is 10Ω ±5%.
This ±5% tolerance means the value of this resistor would be 9.5Ω to 10.5Ω.
Given resistors are only for you for practice. you can comment the answers in the comment below.
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