NEET Practice Questions (MCQs) with Answers & Solutions

In a zener diode, the load current remains approximately constant when the source voltage increases. This is because the zener diode regulates the voltage across the load, ensuring that the load current stays stable even if there are fluctuations in the source voltage.

A varactor diode, also known as a varicap or tuning diode, is specifically designed to act as a variable capacitor when reverse biased. The capacitance of a varactor diode changes with the applied reverse voltage, making it ideal for applications like voltage-controlled oscillators and frequency modulators.

For normal operation of a bipolar junction transistor (BJT), the base-emitter junction is forward biased while the collector-base junction is reverse biased. This allows the transistor to amplify signals or act as a switch. If the collector diode is forward biased, it would not function correctly as a transistor.

In an N-P-N transistor, most of the electrons injected from the emitter into the base diffuse through the base and are collected by the collector. The base is thin and lightly doped, so only a small fraction of electrons recombine in the base, and the majority flow into the collector, allowing the transistor to amplify current.

Let q and 2q be the charges and r the distance between them Then $ 2 \times 10^{-3} = { 2 k q^2 \over r ^2 }$ and $ 5 \times 10^{-4} = { 2 kq^2 \over (r + 0.1 ) ^2 }$ $ so , {20 \over 5 } = { (r + 0.1) ^2 \over r^2 } $ $ \therefore 2 = { r +0.1 \over r^2 } \Rightarrow r = 0.1 m $ Now , substituting the value of r . So obtained 2