HSSC-II (12th Class) Physics Unit-18: Electronics: Numerical Problems List (Punjab Curriculum and Text Board, Lahore) With Verified Answers

18.1 The current flowing into the base of a transistor is 100 μA. Find its collector current Ic, its emitter current Iɛ, and the ratio `\frac {I_C}{I_E}`. If the value of current gain β is 100. Answer (10 mA, 10.1mA, 0.99) 

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18.2 Fig.P.18.2 shows a transistor which operates a relay as the switch S is closed. The relay is energized by a current of 10 mA. Calculate the value R , which will just make the relay operate. The current gain β of the transistor is 200. When the transistor conducts, its `\V_{BC}` can be assumed to be 0.6 V. (Ans: 168 kΩ)

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18.3 In circuit (Fig.P.18.3). there is negligible potential drop between B and E. if. P is 100. Calculate 

(i) base current 
(ii) collector current 
(iv) potential drop across `\R_C` 
(iv) `\V_{CE}`

(Ans: 11.25 μA. 1.125 mA, 1.125 V, 7.875 V) 

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18.4 Calculate the output of the op-amp circuit shown in Fig.P. 18.4. Answer ( 0)

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18.5 Calculate the gain of non-inverting amplifier shown in Fig.P.18.5.  Answer ( 5 )

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Student Learning Output Questions:

Calculate the gain of an amplifier in which the collector resistance Rc is 5 kilo Ohm. The input resistance between the base and emitter of a typical transistor is 2.5 kilo Ohm and the value of its β = 100. Answer (250)