Electronic Circuits

211. What type of coupling is generally used in power amplifiers?

1. Transformer
2. Direct
3. RC
4. Inductive

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212. What type of feedback is used in Wien bridge oscillator?

1. Positive
2. Negative
3. Both positive and negative
4. Either positive or negative

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213. What type of oscillator which is composed of one or more amplifying devices with some frequency determining networks introducing positive feedback at a particular frequency so that oscillation is sustained at that frequency?

1. Sine wave oscillator
2. Square-wave generator
3. Relaxation oscillator
4. Limiter

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214. When a FET with a lower transconductance is substituted into a FET amplifier circuit, what happens?

1. The current gain does not change
2. The voltage gain decreases
3. The circuit disamplifies
4. The input resistance decreases

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215. When a transistor amplifier feeds a load of low resistance, its voltage gain will be

1. Low
2. Very high
3. High
4. Moderate

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216. When a transistor is cut off

1. Maximum current flows
2. Maximum voltage appears across load
3. Maximum voltage appears across transistor
4. Minimum current flows

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217. When amplifiers are cascaded

1. The gain of each amplifier is increased
2. A lower supply voltage is required
3. The overall gain is increased
4. Each amplifier has to work less

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218. When CE configuration is used for an oscillator, the voltage fed back must

1. Be inverted by 180°
2. Be taken from a capacitor
3. Have a 0° phase shift
4. Taken from an inductor

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219. When crystal frequency increases with temperature, it has _________ temperature co- efficient.

1. Positive
2. Negative
3. Zero
4. Infinite

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220. When negative current feedback is applied to an amplifier, its output impedance

1. increases
2. remains unchanged
3. decreases
4. becomes zero

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