Chapter 1 Introduction to Electronics Section 1-1 Atomic Structure 1. Anatom with an atomic number of 6 has 6 electrons and 6 protons, 2 ‘Thetthird shell of an atom can have 2n? = 2(3)° = 18 electrons, Section 1-2 Materials Used in Electronics 3. The materials represented in Figure 1~21 im the textbook are (a) insulator () semiconductor (©) conductor 4. An atom with four valence electrons is a semiconductor. 5. Inasilicon crystal, each atom forms four covalent bonds. Section 1-3 Current in Semiconductors 6. When heat is added to silicon, more free electrons and holes are produced. 7. Current is produced in silicon at the conduction band and the valence band. Section 1-4 N-Type and P-Type Semiconductors 8. Doping is the carefully controled addition of trivalent or pentavalent atoms to pure intrinsic) semiconductor material for the purpose of inereasing the number of majority cariers (free electrons or holes), 9 Antimony is a pentavalent (donor) material used for doping to increase free electrons. Boron is a trivalent (acceptor) material used for doping to increase the hol Section 1-5 The PN Junction 10, The electric field across the pn junction of a diode is created by donor atoms in the n region losing free electrons to acceptor atoms in the p region. This creates positive ions in the ‘m region near the junction and negative ions in the p region near the junction, A field is then established between the ions LL, The barrier potential of a diode represents an energy gradient that must be overcome by conduction electrons and produces a voltage drop, not a source of energy.Chapter 2 Diode Applications Section 2-1 Diode Operation 1 ‘To forward-bias a diode, the positive terminal of a voltage source must be connected 10 the: p region. A series resistor is needed to will not damage the diode beca nit the current through a forward-biased diode to a value that use the diode itself has very little resistance, Section 2-2 Voltage-Current Characteristic of a Diode 3 ‘To generate the forward bias portion of the characteristic curve, connect a voltage source across the diode for forward bias and place an ammeter in series with the diode and voltmeter across the diode. Slowly increase the voltage from zero and plot the forward voltage versus the current A temperature increase would cause the barrier potential of a silicon diode to decrease from 0.7 V 006 V. Section 2-3 Diode Models (a) The diode is reverse-biased. (b) The diode is forward-biased. (©) The diode is forward- biased. (A) The diode is forward-biased, (a) Ve=5V-8V (b) 7 (© Ve =0.7V (@) Ve=07V (@) Va=5V-8V (b) Ye=0V v v © @ Ignoring 7 (a) Ve = 5V-8V (b) p= WON=OTV rh ma 02102 Ve= ery + Va = (174 mA)(10 @) + 0.7 V = 2.44 VChapter 2 30V CC) Troe 20 SON. 6.19 mA R, 485K2 tp= 219A 5m Ve= ler) +0.7 V = G.1 mAX10.Q) 40.7 V =0.731 V (d) Approximately all of the current from the 20 V source is through the diode. No current from the 10 V source is through the diode, 20V-07V 10kKQ+1B Vp = (1.92 mA)UO Q) +0.7 V = = 1.92 mA 719 V Section 2-4 Half-Wave Rectifiers 9 See Figure 2-1 Figure 2-1 10. (@) PIV=V, =5¥ (b) PIV= V, =50V u. % 2 @) f= 43V Lo1sma R 47a. Virw-O.7V _S0V-0.7V _493V _ (by tp ee RY BY = 149mA 1B. Vi. =nVj, = (0.2120 V = 24 V rms 1 Vi. =n¥V,,=(0.5)120 V = 60 Vims Vices) = 1414(60 V) = 84.8 V ¥, : y ser _848V _srgy