. Assertion: Light emitting diode (LED) emits spontaneous radiation.
Reason: LED are forward biased p-n junctions.
Solution: When a junction diode is forward biased as shown in figure, energy is released at the junction due to recombination of electrons and holes. In the junction diode made of gallium arsenide or indium phosphise, the energy is released in visible region. Such a junction diode is called light emitting diode or LED. The radiated energy emitted by LED is equal or less than the band gap of semiconductor.