What will happen if you connect an LED up to a battery without any resistor in the circuit?
a flash and a shot with a puff of smoke.
nothing will be br happrn
led will trun on
if the voltage exceeds the voltage required by the led it will probably burn. if the voltage is lower, the LED may not light up or be much weaker.
Enough often, you let the smoke out. it is possible with coin-operated batteries. they have an internal resistance high enough to prevent the roasting of the led. but with something like aa battery, the led is the story.
you will come back in time. to return to the present or future, simply reverse the polarity.
The speed with which you climb or go back in time depends on the tension. Pay attention!
I put some 3v led into the headphones of my master chef (video game character) he was wearing for Halloween. I first tried to wire them in series, directly on a 9v battery. they burned in about 2 seconds. Then I put a resistance in the circuit and they worked well.
If the voltage of the battery exceeds the direct voltage drop of the LED and can deliver a current greater than 50 mA, and the LED is connected in the forward direction, it will “blow” immediately, possibly with a loud burst . you may see a lightning bolt when the light comes on briefly before exhaling. some older types may last a little longer, shine for a brief moment, followed by a much weaker glow for a few seconds, then finally no light at all.
The. now, you know, you do not have to lose a perfect opportunity for this “experience”. it’s not very spectacular.
it is currently manufactured in a led flashlight keychain, but only causes the operating voltage of the led is 3.2 volts and a cr2032 can put very little power (something like 6 my pulsed ).
In general, above the threshold voltage, the current is exponential with the voltage.
for example: a typical white nichia LED operates at 3.2 volts and 20 mA; if the voltage reaches 4 volts, the current reaches 90 mA or more than 5 times the nominal power.
this is the reason why power LEDs are classified as current; you must therefore use a constant current driver or at least a
series resistor if the voltage of the battery terminal is greater than the front fall of the indicator, usually 2v for the red lights, can be 3v for the blue and some other colors …
with only the fraction of a ohmic resistance of a typical battery, a large current will circulate. if the battery can deliver a large current of several hundred milliamps or more, it is likely that the indicator will discharge quickly.
If the voltage across the battery is lower than the direct voltage of the led, little current will flow and the led will not light.
If you are lucky and the battery voltage is at the diode, the current will be somewhat limited but a bit unpredictable. it is likely that the light will come on a bit. it is in a region of the diode curve that changes radically and will not be stable at all with the temperature and voltage of the battery. Indicator lights can still have easily visible amounts of light ranging from about one milliamp to 50 milliamps, a range of 50: 1.