COMEDK 2025 Evening Shift | Semiconductor Devices and Logic Gates Question 3 | Physics

An intrinsic semiconductor has equal concentrations of hole and electron which is equal to $4 \times 10^8 \mathrm{~m}^{-3}$. During its conversion to extrinsic semiconductor, concentration of hole increases to $8 \times 10^{10} \mathrm{~m}^{-3}$. The new electron concentration is:

$4 \times 10^8 \mathrm{~m}^{-3}$

$2 \times 10^8 \mathrm{~m}^{-3}$

$2 \times 10^6 \mathrm{~m}^{-3}$

$4 \times 10^{10} \mathrm{~m}^{-3}$

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COMEDK 2025 Afternoon Shift Physics - Semiconductor Devices and Logic Gates Question 4 English

Three ideal diodes and resistors connected to the cell of negligible internal resistance is as shown. Find the current passing through the $10 \Omega$ resistor.

1 A

2 A

0.5 A

0.1 A

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Diamond is considered as an insulator because

Diamond has very large forbidden energy gap.

Valance band and conduction band of diamond are overlapping X .

In the diamond the carbon atoms are held by weak covalent bonds

Refractive index of diamond is very low

COMEDK 2025 Afternoon Shift

MCQ (Single Correct Answer)

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What is the maximum wave length of EM radiation required to move an electron from the valance band to conduction band of a semiconductor? [Given :Energy gap $\mathrm{E}_{\mathrm{g}}=1.98 \times 10^{-19} \mathrm{~J}$; Planck's constant $h=6.6 \times 10^{-34} \mathrm{Js}$ ]

$10^{-9} \mathrm{~m}$

$10^{-6} \mathrm{~m}$

$10^{-10} \mathrm{~m}$

$10^{-12} \mathrm{~m}$

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