Solid State Devices

181. The way in which the gain of an amplifier varies with the frequency is called

1. Logarithmic response
2. Frequency response
3. Voltage response
4. Phase response

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182. There are two mechanisms by which holes and electrons move through a silicon crystal. They are

1. Covalent bond and recombination
2. Diffusion and drift
3. Free and charge particles
4. Forward and reverse bias

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183. Thermal voltage Vt is approximately equal to _________ at room temperature (20°C)

1. 25 mV
2. 25 V
3. 100 mV
4. 100 V

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184. Two pn silicon diodes are connected in series opposing. A 5 V voltage is impressed upon them. Find the voltage across each junction at room temperature when nVT= 0.052 V.

1. 0.236 V, 3.2 V
2. 4.764 V, 0.236 V
3. 0.036 V, 4.964 V
4. 3.21 V, 1.79 V

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185. Typical leakage current in a pn junction is in the order of

1. µA
2. mA
3. nA
4. pA

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186. Under standard conditions, pure germanium has a resistivity of

1. 60 Ω-em
2. 60 Ω-m
3. 60 Ω-mm
4. 60 x 10^-4

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187. Unijunction transistor has three terminals, namely

1. Gate, cathode and anode
2. Grid, plate and cathode
3. Base 1, base 2 and emitter
4. Gate, base 1 and base 2

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188. Valence orbit is the other form for

1. Outer orbit
2. 3rd orbit
3. 4th orbit
4. 2nd orbit

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189. Varactor diode's transition capacitance is directly proportional to the product of the permittivity of the semiconductor material and PN junction area but inversely proportional to its

1. Resistance
2. Voltage
3. Depletion width
4. Threshold voltage

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190. Varactor diodes are commonly used

1. As voltage controlled capacitance
2. As a constant current source
3. As voltage multiplier
4. As a constant voltage source

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