Most LEDs have one lead longer than the other, or a flat side on the rim of the
base, to indicate polarity. An LED that has neither of these must be marked in
some other way.
The only way to identify the polarity of an unmarked LED is to test it. A common AA
or C battery in series with a small resistor of 50-100 ohms will do the job.
The LED lights when the positive end of the battery ... possibly through the resistor ...
goes to the positive end of the LED. (There is no harm to the LED when the battery is
connected backwards and the LED doesn't light.)
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Positive + Negative = Negative Negative + Negative = Positive Positive + Positive = Positive Negative + Positive = Negative
If the negative number is bigger then the answer will be negative If the bigger number is positive then the answer will be positive. All you do is subtract the two numbers and take the sign of the bigger number Ex (+2)+(-7)=(-5)
The rules for the sign (positive or negative) of the result of a multiplication is the same as division. For multiplication: Positive * Positive --> Positive Positive * Negative --> Negative Negative * Positive --> Negative Negative * Negative --> Positive For division: Positive / Positive --> Positive Positive / Negative --> Negative Negative / Positive --> Negative Negative / Negative --> Positive
a negative x a negative= a positive, a positive x a positive= a positive, a negative x a positive= a negative, and a positive x a negative= a negative. Same thing with division. a negative divided by a negative= a positive, a positive divided by a positive= a positive, a negative divided by a positive= a negative, and a positive divided by a negative is a negative. U see?
positive 49 Because a negative times a negative is a positive. -7*-7=49. positive * positive = positive negative * negative= positive positive * negative = Negative