MCQs

If Ic is 100 times larger than Ib, then βDC is: 100 10 1 0.01 Correct answer: 1. 100

The zener impedance for range in which 5 mA change in zener current produces a 0.3 V change in zener voltage: 15 Ω 30 Ω 45 Ω 60 Ω Correct answer: 4. 60 Ω

Compared to a visible red LED, an infrared LED: Produces light with shorter wavelength Produces light when reverse-biased Produces light with longer wavelengths Produces only one color of light Correct answer: 1. Produces light with shorter wavelength

Zener diode is doped in which manner: Lightly Moderately Heavily Correct answer: 3. Heavily

The depletion region of which diode acts as a capacitor dielectric: General purpose diode Zener diode Varactor diode Optical diode All of these Correct answer: 3. Varactor diode

For operating BJT as an amplifier the base of npn transistor must be: negative with respect to the emitter positive with respect to the collector positive with respect to the emitter Any of above Correct answer: 3. Positive with respect to the emitter

A BJT transistor when operated in cutoff and saturation it acts like: A variable inductor A linear amplifier A variable capacitor A variable resistor A switch Correct answer: 5. A switch

An LED Exhibits variable capacitance Emits light when forward-biased Emits light when reverse-biased Acts as a variable inductance Correct answer: 2. Emits light when forward-biased

Zener diodes having breakdown voltages of 2. 5 V will operate in: Zener breakdown avalanche breakdown Both of these None of these Correct answer: 1. Zener breakdown

Generally, the cathode of Zener diode in a voltage regulator is: Forward biased Reverse biased at + 0.7 V grounded Correct answer: 2. Reverse biased