Practice Section
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Target time per problem: Easy (1 min), Medium (2 min), Hard (3-4 min)
Target time per problem: Easy (1 min), Medium (2 min), Hard (3-4 min)
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Level 1: Easy (CBSE / NEET Easy)
Practice 1 Easy
Pure germanium is doped with indium. What type of semiconductor is formed and what are the majority carriers?
Practice 2 Easy
In an intrinsic semiconductor at room temperature, if n = 1.5 × 10¹⁰ cm⁻³, find p.
Practice 3 Easy
An LED emits light of wavelength 550 nm. Calculate its band gap energy in eV.
Practice 4 Easy
What is the output of a NAND gate when both inputs are 1?
Practice 5 Easy
What happens to depletion width when a p-n junction is forward biased?
Level 2: Medium (NEET / JEE Main)
Practice 6 Medium
A full-wave rectifier has a peak AC voltage of 28 V. Calculate the DC output voltage.
Practice 7 Medium
In an n-type semiconductor, electron concentration is 10¹⁶ cm⁻³. If ni = 1.5 × 10¹⁰ cm⁻³, find hole concentration.
Practice 8 Medium
A diode has a forward voltage of 0.7 V at 10 mA and 0.8 V at 50 mA. Calculate dynamic resistance.
Practice 9 Medium
Half-wave rectifier input is 50 Hz AC. What is the output frequency?
Practice 10 Medium
A Zener diode with VZ = 6 V is connected to a 12 V supply through a 300 Ω resistor. Find the Zener current.
Level 3: Hard (JEE Main Advanced)
Practice 11 Hard
A full-wave rectifier uses a transformer with secondary voltage 20 V RMS. If load is 500 Ω, calculate:
(a) Peak voltage (b) DC voltage (c) DC current (d) DC power
Practice 12 Hard
A GaAs LED has band gap 1.43 eV. Calculate wavelength and identify if it's in visible range. (h = 6.63×10⁻³⁴ J·s, c = 3×10⁸ m/s)
Practice 13 Hard
Simplify the logic expression: Y = (A·B) + (A̅·B̅). What single gate can replace this?
Practice 14 Hard
Compare efficiency of half-wave vs full-wave rectifier. If half-wave delivers 10 W DC power, what would full-wave deliver from same transformer?
Practice 15 Hard
A photodiode receives light of intensity 100 W/m² over area 1 cm². If wavelength is 600 nm and 25% photons generate e-h pairs, find the photocurrent.
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