CBSE Physics Solids and Semiconductor Devices Test 2 Online

1. A transistor is operated in common emitter configuration at constant collector voltage V_c = 1.5 V such that a change in the base current form 100 A to 150 A produces a change in the collector current form 5 mA to 10 mA. The current gain (β)is ?

2. Chose only false statement from the following ?

3. If a full wave rectifier circuit is operating form 50Hz mains, the fundamental frequency in the ripple will be ?

4. A transistor-oscillator using a resonant circuit with a inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency f. If L is doubled and C is changed to 4 C, the frequency will be ?

5. Zener diode is used for ?

6. The circuit is equivalent to ?

7. A transistor is operated in common-emitter configuration at V_c = 2 volt such that a change in the base current from 100 μA to 200 μA produces a change in the collector current form 5 mA to 10mA. The current gain is ?

8. Carbon, silicon and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (E_g)_c, (E_g)_si and (E_g)_Ge respectively. Which one of the following relationships is true in their case ?

9. The symbolic representation of four logic gates

The logic symbols for OR, NOT and NAND gates are respectively ?

10. Sodium has body centre packing. Distance between two nearest atoms 3.7 A°. The lattice parameter is ?

11. Application of a forward bias to a p-n junction ?

12. In semiconductors at a room temperature ?

13. The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be ?

14. Copper has face-centered cubic (fcc) lattice with interatomic spacing equal to spacing equal to 2.54 A°. The value of lattice constant for this lattice is ?

15. A n-p-n transistor conducts when ?

16. In the energy band diagram of a material shown below, the open circles anα filled circles denote holes and electrons respectively. The material is a/an ?

17. In a p-n junction photo cell, the value of the photo-electromotive force produced by monochromatic light is proportional to ?

18. The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without filter is 10V. The DC component of the output voltage is ?

19. A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly ?

20. A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength ?

21. If the lattice parameter for a crystalline structure is 3.6 A°, then the atomic radius in fcc crystal is ?

22. For a cubic crystal structure which one of the following relations indicating the cell characteristic is  correct ?

23. A common emitter amplifier has a voltage gain of 50, an input impedance of 100 Ω and an output impedance of 200 Ω. The power gain of the amplifier is ?

24. The output of OR gate is 1 ?

25. The following figure shows a logic gate circuit with two inputs A and B and the output C. The voltage waveforms of A, B and C are as shown below ?