Question

The longer lead of a LED is always connected to the negative terminal of the battery and the shorter lead is connected to the positive terminal of the battery:
A. True
B. False
C. Ambiguous
D. Data insufficient

Answer 1

Hint: A semiconductor is defined as the material that has the electrical conductivity value falling in between that of a conductor, such as copper and an insulator, such as glass or rubber. The advantage of using a semiconductor is that its use can be modified by introducing impurities in a process called doping to enhance its functionality.

Complete step-by-step answer:
The full form of LED is called Light-Emitting Diode. A light emitting diode is a semiconductor light source that emits light when there are current flows through it. Thus, the LED is a special type of a semiconductor P-N junction diode with additional light-sensitive dopants like gallium arsenide (GaAs) and gallium nitride (GaN).
When the diode is connected to an external circuit, the electrons on the N-side recombine with the holes in P-side and these electrons emit a radiation of wavelength in the visible spectrum depending upon the dopant associated with a particular colour such as blue, red or green or even infrared.
In order for the diode to work, the diode must be operated in Forward Bias. Forward bias means connecting the positive terminal of the battery to the P-side and the negative terminal of the battery to the N-side.

Here, we can see two steel wires called as leads. One lead is longer than the other. The longer lead of the two represents the P-side and this must be connected to the positive terminal of the battery and the shorter lead of the two represents the N-side and this must be connected to the negative terminal of the battery.
Thus, the statement in the question: The longer lead of a LED is always connected to the negative terminal of the battery and the shorter lead is connected to the positive terminal of the battery is False.
The correct option is Option B.

Note: One might wonder what can happen if the leads can be interchanged. This can lead to a disaster. Once the diode is connected in the other way, the diode is under reverse bias. When a diode is under reverse bias, initially, the current flowing is very low but only up to a voltage point called breakdown voltage. Once, the external bias voltage reaches the breakdown voltage, it breaks the barrier and large amounts of current can flow through the LED not only destroying the LED but also, causing a short-circuit. Therefore, one should be aware and careful while connecting a diode in the circuit.