octubre m4 ase fundamentos electricidad

1) What gives the colour of an LED?. The active element. The plastic it is encased in. The type of gas used inside it.

2) A germanium diode is used for. rectification. voltage stabilization. modulation.

3) Why is a diode put in parallel with an LED?. To protect it from AC. So it will work only above a certain voltage. So it will work only below a certain voltage.

4) When testing the forward bias of a diode with a multimeter. the positive lead of the ohmmeter is placed on the anode. it does not matter which terminal the positive lead of the ohmeter is placed. the positive lead of the ohmmeter is placed on the cathode.

5) Which of the following describes the characteristics of a Thyristor?. High voltage handling. High power handling. High current handling.

6) Light Emitting Diodes (LEDs). emit light of only one wavelength dependent on type. have very wide viewing angles. are easily damaged if forward biased b more than 5V.

7) In a semiconductor junction diode, electrons are the minority carriers. within the P region. within the N region. in both the N and P regions.

8) A silicon diode, when compared to a germanium diode has. a higher forward bias voltage. the same forward bias voltage. less forward bias voltage.

9) A zener diode. allows current to flow in one direction. stabilizes voltage at a predetermined level. acts like a switch.

10) A junction diode. is similar to a vacuum diode but cannot rectify. has one p-n junction. can handle only very small currents.

11) Reverse bias. raises the potential barrier. lowers the potential barrier. greatly increases the majority carrier current.

12) A diode connected across a relay coil is used to. dissipate coil spikes on switch off. allow the coil to energize with only one polarity. cause a delay in switching on.

13) To check the forward resistance of a diode with a multimeter, the lead connected to the positive terminal is put to the. anode. cathode. either anode or cathode.

14) A thyristor has which of the following?. A positive temperature coefficient. High resistance when switched off. High resistance when switched on.

15) In an LED, what is used to make the colour?. The plastic lens cover. The electron. The doping material.

16) An atom with 5 electrons in its outer shell is part of. a C type material. a P type material. an N type material.

17) A thyristor is commonly used for. overvolts regulation. voltage regulation. rectification.

18) A diode which emits photons when conducting is a. light emitting. varactor. zener.

19) The electrodes of an SCR are. gate, cathode, anode. source, drain, gate. anode, cathode, source.

20) What gives an LED its colour?. A gas. The cover. Composition and impurity of the compound.

21) Forward voltage of a silicon diode is. 1.6v. 0.6v. 0.2v.

22) What is the typical volts drop across an LED. 0.2v. 0.4v. 1.6v.

23) What diode gives off light photons when forward biased. LED. Gunn diode. Schottky diode.

24) The anode of a diode is connected to a +4V DC supply and the cathode is connected to a +2V DC supply. The diode is. forward biased not conducting. reverse biased not conducting. forward biased conducting.

25) Using electron flow in a diode the current flows from. Anode to Cathode. Cathode to Base. Cathode to Anode.

26) When a hole diffuses from the pregion to then region. raises the potential barrier. it becomes a minority carrier in the n region. lowers the potential barrier.

27) A junction diode. can handle only small currents. is similar to a vacuum diode but cannot rectify. has one p-n junction.

28) A germanium diode. has a lower forward bias voltage than a silicon diode. has a higher forward bias voltage than a silicon diode. has the same forward bias voltage as a silicon diode.

29) What switches off a thyristor?. Reverse bias gate. Remove the gate voltage. Remove supply voltage.

30) When an SCR is switched on it has. low resistance. no change in resistance. high resistance.

31) What type of pulse is required to switch on an SCR?. Positive. Negative. Positive or negative.

32) A piece of pure Germanium. is electrically stable. has a deficit of electrons. has an excess of electrons.

33) When a diode is forward biased, current flow is mainly due to the. germanium bias junction. majority carriers. minority carriers.

34) When a diode is forward biased the. positive lead is connected to both N and P type. positive lead is connected to the N type and negative to the P type. positive lead is connected to the P type and negative to the N type.

35) What are the majority carriers for a forward biased PN junction device?. Electrons and holes. Holes. Electrons.

36) Germanium in its pure state is. negatively charged. neutral. positively charged.

37) Which diode has a lower forward bias voltage?. Silicon. Germanium. Both have the same forward bias voltage.

38) A Zener diode is used for. voltage stabilisation. rectification. voltage regulation.

39) A thyristor SCR is a. bi-directional device. unidirectional device. multidirectional device.

40) What component is used to turn AC to DC?. Thyristor. Diode. Transistor.

41) What is an intrinsic material?. One with added elements. One with removed elements. A pure material.

42) A diode is parallel to an LED in an AC circuit to. provide correct amount of current for LED when circuit is switched on. prevent back EMF in the circuit when LED is switched off. protect LED from AC current when switched on.

43) In a forward biased diode, current is carried by. majority carriers. both. minority carriers.

44) When checking a diode for reverse bias resistance the positive lead goes to. anode and negative lead to earth. cathode and negative lead to anode. anode and negative lead to cathode.

45) Zener diodes are used for. Current control. Voltage control. Temperature control.

46) Once started conducting an SCR switches off. only when the anode goes negative to the cathode. automatically after a specific time. only when the anode goes positive to the cathode.

47) In a forward biased diode, electrons leave the. the anode. the cathode. the doped area.

48) Diodes are. conductors. semi-conductors. Insulators.

49) To function, i.e. conduct, a junction diode made of silicon requires a forward bias of at least. 0.2v. 1.41v. 1v.

50) What is the average gain of an Op Amp?. 20. 200,000. 200.

51) Tunnel diodes have the following characteristics: Heavily doped P-N junction with an extremely narrow depletion region. Lightly doped P and N regions and a high reverse breakdown voltage. Lightly doped P region, heavily doped N region and has a fast response time.

52) The capacitance of a varactor diode is. inversely proportional with reverse bias voltage. a linear function of applied reverse bias voltage. directly related to the forward bias voltage.

53) A semiconductor doped with an element having a valency of 5 will produce. an N type material. either an N type or a P type depending on what type of semiconductor material is used. a P type material.

54) In a diode clamper, if the resistor is removed making the time constant equal to C x r where r is the reverse resistance of the diode, this will ensure a . long time constant. short time constant. Very Long Time Constant.

55) PIN diodes are used mainly for. linear rectifiers. fast switching devices. voltage operated rectifiers.

56) To enable an IMPATT diode to operate correctly, it must be. connected to a resonant circuit. used in its reverse bias mode. operated in its negative resistance range.

57) What type of diode would be used to stop voltage spikes across a coil of a relay?. Schottky diode. Zener diode. Gunn diode.

58) What is a schottky diode used for? . Rectification. Stabilization. Very high frequency applications.

59) When a hole diffuses from a p-region to the n-region it. becomes a minority carrier in the n-region. lowers the potential barrier. raises the potential barrier.

60) The junction barrier offers opposition to only. holes in the p-region. free electrons in the n-region. majority carriers in both regions.

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