Opto Quizes

In the depletion region of a P-N junction, there is a shortage of ______________________. Ans: Holes and Electrons

In an intrinsic semiconductor, the number of conduction electrons is 7x10^19 m^3. ______________________ is the total number of current carriers in the same semiconductor of size 1 cm × 1 cm × 1 mm. Ans: 14x10^12

The leakage current across a P-N junction is due to ______________________. Ans: minority carriers

An N-type semiconductor has hall coefficient = 4.16x10^-4 m^3 C^-1. The conductivity is 108^–1 m^–1. The electron mobility at room temperature is ______________________ m^2/v/s. Ans: 0.0381 

The energy gap of silicon is 1.14 eV. The maximum wavelength at which silicon will begin absorbing energy is ______________________ Angstrom. Ans: 10888

A p-type semiconductor has acceptor levels 57meV above the valance band. The maximum wavelength of light required to create a hole is ______________________ Angstrom. Ans: 217100

For ______________________ density of electrons is equal to the density of holes. Ans: intrinsic semiconductors

When a pure semiconductor is heated, its resistance ______________________. Ans: decreases

At Absolute zero, a semiconductor behaves like ______________________. Ans: a perfect insulator

A wavelength of the laser beam can be used to measure the ______________________. Ans: Length

The external power efficiency of the LED device is ______________________. Ans: 10%

The LEDs made with GaAs emit light in the ______________________. Ans: Infrared region

What is the need to achieve population inversion ______________________. Ans: to achieve a stable condition for photo electric emission

When forward-biased, LED emits light because of ______________________. Ans: recombination of carriers

A simple P-N junction diode is fabricated using ______________________ semiconductor and can be used as a ______________________. Ans: extrinsic, unidirectional switch

The following is not a candidate material for Laser source in Fiber optics. Options: a. He-Ne, b. Phosphorous, c. Argon, d. Nd-YAG. Ans: Phosphorous

The battery connections required to forward bias a P-N junction are ______________________. Ans: +ve terminal to p and -ve terminal to n

The helium atom in a helium-neon laser works as ______________________. Ans: energy supplier

What should be the biasing of the LED? Ans: Forward biasing

Which of the following is not a characteristic of LED? Options: a. High Warm-up time, b. Long life, c. Fast action, d. Low operational voltage. Ans: High Warm-up time

Which process of the Electron-hole pair is responsible for emitting of light? Ans: Recombination

In a Ruby laser, the color of laser light is due to ______________________ atom. Ans: Chromium

Ruby laser is a solid-state laser, the active medium is ______________________. Ans: crystalline substance

A light emitting diode is ______________________. Ans: both visible and invisible light

The spontaneous emission produces ______________________. Ans: incoherent light

The condition for population inversion is ______________________. Ans: N2/N1=exp-((E2-E1)/kT)

Optical pumping is suitable for any medium which is ______________________. Ans: transparent light

Which of the following is an important property of LASER? Options: a. Irradiance, b. Divergence, c. Coherence, d. Monochromacity. Ans: Coherence

The photo-diode can turn its current ON and OFF in ______________________ seconds. Ans: nano

Which of the following is a gas LASER ? Options: a. He-Ne Laser, b. Ruby Laser, c. Nd-YAG Laser. Ans: He-Ne Laser

The main principle of optical fiber is ______________________. Ans: Total internal reflection

Which of the following materials can be used to produce infrared LED? Options: a. Si, b. GaAs, c. CdS, d. None of the above. Ans: GaAs

The maximum wavelength of photons that can be detected by a photo-diode made by a semiconductor of band gap 2eV is about ______________________. Ans: 620 nm

Which one of the following an be used as a photodetector in Fiber Optic Communication ? Options: a. PIN diode, b. Laser diode, c. LED, d. Tunnel diode. Ans: PIN diode

An LED has lower output power, ______________________ switching speed and ______________________ spectral width than the LASER as an optical source. Ans: slower, higher

Which of the following is not part of the laser system? Options: a. Active medium, b. Optical resonator, c. Pumping mechanism, d. Optical activity. Ans: Optical activity