Semiconductors Lesson 7

Find the value for RL when IC = 20 mA and VCE = 20 V.

0

Find the value for IC when RS = 1 KΩ, VCE = 20 V, and RL = 0 Ω.

0.1A

Find the value for RL when IC = 20 mA and VCE = 0 V.

1000ohm

Saturation occurs at ? .

20mA

Find the value for RL when IC = 20 mA and VCE = 10 V.

500ohm

If beta of a transistor is 200 and IC is 12 milliamps, what is the base current in microamps?

60 IB= IC/B 0.012/200 = 60

Which schematic symbol represents the NPN BJT?

A

What test instrument may be used to determine if a transistor is NPN or PNP type?

A digital multimeter

Match each junction in the image to its name.

A-Collector,B-Base,C-Emmitter

Why is the NPN transistor more widely used than the PNP?

All of the above

The relationship between the emitter current and the collector current in a BJT is called ? .

Alpha

Which schematic symbol represents the PNP BJT?

B

Which transistor configuration is very useful as an isolation amplifier and is often called an emitter follower?

Common Collector

The ? is the most popular configuration, and application is universal.

Common Emmitter

Which of the transistor configurations has a voltage phase reversal due to the collector voltage being 180° out of phase with the input base voltage?

Common Emmitter

At ? , the transistor passes nearly no current across E-C (like an open switch).

Cutoff

Beta is the amount of DC voltage gain in a transistor. It is a relationship between the DC collector voltage to DC base voltage.

False

Collector characteristic curves indicate changes in base current with respect to changes in collector current.

False

In normal operation of the BJT type transistor, the B-E junction must be reverse biased, and the C-B junction must be forward biased.

False

When testing an NPN transistor with the ohmmeter leads connected ("+ Collector" "− Base"), one should be reading low resistance values.

False

When testing an NPN transistor with the ohmmeter leads connected ("+ Collector" "− Emitter"), one should be reading low resistance values.

False

When testing an NPN transistor with the ohmmeter leads connected ("+ Emitter" "− Base"), one should be reading low resistance values.

False

When testing an NPN transistor with the ohmmeter leads connected ("− Collector" "+ Emitter"), one should be reading low resistance values.

False

Which of the following methods can be used to prevent transistor thermal instability?

I. Installation of a heat sink II. Use of a feedback circuit III. Use of a voltage divider circuit

Find the value for IC when RS = 100 kΩ, VCE = 20 V, and RL = 0 Ω.

IB=VRS/RS 2/100000= 20... IC=IBxB= 0.000002x50 = 0.001A

Find the value for IC when RS = 250 kΩ, VCE = 20 V, and RL = 0 Ω.

IB=VRS/RS 2/250000= 8...IC=IBxB 0.000008x50 =400

Find the value for IC when RS = 25 kΩ, VCE = 20 V, and RL = 0 Ω.

IB=VRS/RS 2/250000=80...IC=IBxB= 0.0000080x50=0.004A

Find the value for IC when RS = 50 kΩ, VCE = 20 V, and RL = 0 Ω.

IB=VRS/RS 2/50000.. IC=IBxB 0.0000040x50= 0.002A

Find the value for IC when RS = 500 kΩ, VCE = 20 V, and RL = 0 Ω.

IB=VRS/RS 2/500000=4...IC= IBxB 0.000004x50= 200

Find the value for IC when RS = 10 kΩ, VCE = 20 V, and RL = 0 Ω.

IC= 0.01A

Find the value for IC when RS = 5 kΩ, VCE = 20 V, and RL = 0 Ω.

IC=0.02A

Which of the following formulas represents emitter current during normal operation?

IE=IC+IB

During ? , B-E is forward biased and C-E is reverse biased.

Saturation

If the NPN transistor in the image was replaced with a PNP type, what changes to the circuit would be necessary?

The polarity of both power sources would have to be reversed.

The PNP transistor is based on hole current where the NPN transistor is based on electron current.

True

The bipolar junction transistor is made up of either a NPN junction or a PNP junction.

True

The two extremes of a load line are saturation and cutoff points.

True

When testing an NPN transistor with the ohmmeter leads connected (" − Emitter" "+ Base"), one should be reading low resistance values.

True

When testing an NPN transistor with the ohmmeter leads connected ("− Collector" "+ Base"), one should be reading low resistance values.

True

Find the value for RL when IC = 2 mA and VCE = 0 V.

VRL=VCC-VCE=20-0=20V.. RL=VRL/IC.. 20/0.002= 10000ohm

Find the value for RL when IC = 2 mA and VCE = 10 V.

VRL=VCC-VCE=20-10=10V.. RL=VRL/IC.. 10/0.002= 5000ohm

A current-controlled, three-terminal semiconductor device used for the control and amplification of electronic circuitry is called a(n) ? .

bipolar junction transistor