MCQ
An LED emits visible light when its
  • A
    junction is reverse biased
  • B
    depletion region widens
  • holes and electrons recombine
  • D
    junction becomes hot.

Answer

Correct option: C.
holes and electrons recombine
holes and electrons recombine

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

In an oscillator, for sustained oscillations, Barkhausen criterion is $A \beta$ equal to $(A=$ voltage gain without feedback, $\beta=$ feedback factor)
A wheel of moment of inertia $2 kg m ^2$ is rotating about an axis passing through centre and perpendicular to its plane at a speed $60 rad / s$. Due to friction, it comes to rest in 5 minutes. The angular momentum of the wheel three minutes before it stops rotating is
An alternating voltage is given by $E=100 \sin (\omega t+\pi / 6) V$.The voltage will be maximum for the first time when $t=[T=$ periodic time $]$
Two capacitors each of capacitance $4 \mu F$ are connected in series, and a third capacitor of capacitance $4 \mu F$ is connected in parallel with the combination. Then, the equivalentcapacitance of the arrangement is
Huygens' principle is used to
The rms speed of the molecules of a gas is $200 \mathrm{~m} / \mathrm{s}$ at $27^{\circ} \mathrm{C}$ and 1 atmosphere pressure. The rms speed at $127^{\circ} \mathrm{C}$ and double the pressure is
When the null point is obtained in the potentiometer, the current is drawn from the ______
In vertical circular motion, the ratio of kinetic energy of a particle at highest point to that at lowest point is
Two parallel plates, separated by a distance $d$, are kept at potential difference $V$ volt. A. charge $q$ of mass $m$ enters between the parallel plates with some velocity. The acceleration of the charged particle will be