Hi, In this video I'll explain "Why a resistor can burn?"
A resistor is a passive two terminal component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels etc.
By applying too high voltage to a resistor, the resistor will have to dissipate too much current. This causes excessive power to be dissipated in the resistor which makes it go up in flames.
■ How It Works
In the video, a 50Ω ¼W resistor and 24V from a power supply is used. (That's a 50 ohm quarter watt resistor and a 24 volt power supply).
The power that is dissipated in the resistor is calculated by multiplying the voltage across the resistor by itself and then dividing that result by the value of the resistor. In our example this is (24V × 24V) ÷ 50Ω = 11,52W (11,52 Watts). The little resistor is only rated at ¼W (0.25 Watts), but we are attempting to dissipate 11,52 Watts into it, that is 11,27 Watts too much! (11,52W – 0,25W = 11,27W).
This is why you see the smoke and flame.
■ The Mathematics
The equation for calculating the power that is dissipated in the resistor is:
P = (V × V) ÷ R
Where:
P is the power dissipated in the resistor
V is the voltage across the resistor
R is the resistance of the resistor
The current flowing though the resistor can be calculated using Ohm's law:
I = V ÷ R
In our example, 0,48A tries to flow through the resistor. (I = 24V ÷ 50Ω)
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Music: Ikson - Skyline
Video Thumbnails: by Google Images
WARNING: This video is only for demonstration. I don't take any responsibility for damage to things, people and animals.
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