4SIMPLE PHYSICS QUESTIONS

Chapter 3 Problems: 1, 2, 5, 6, 9, and 13

1 .

What is the exact value of IC for IE = 5.34 mA and IB = 47.5 μA?

Use the equation Ic + Ib = Ie  put the values we get Ic + 47.5 x(10) -6 = 5.34 x (10) -3  or Ic + 47.5/1000000 = 5.34/1000 or Ic + 0.0000475 = 0.00534 or Ic = 0.00534 - 0.0000475  or Ic = 0.0052925 or Ic = 52925/10000000 or Ic = 52925x (10) -7 or Ic = 5.2925 x (10) -3  or Ic = 5.2925mA because, 1mA = (10) -3 A

2.

A certain transistor has an IC = 25 mA and an IB = 200 μA. Determine the βDC.

IB=IC / ß  is the fundamental operational equation for the bipolar equation. It says that the collector current is dependent only on the base current.

 

Therefore re-arranging the equation gives us ß = IC / IB

 

You have to convert Both IC and IB to Amps for

IC= 25e-3 A

IB= 200e-6 A

 

Therefore the resulting ß = 125 (This is the current gain). It simply means that a small base current when amplified by the gain can control the collector current

5 .

Determine the IB, IC, and VC for the transistor circuit in Figure 3–66 . Assume βDC = 75.

FIGURE 3–66

6.

Draw the dc load line for the transistor circuit in Figure 3–67 .

FIGURE 3–67

8.

For the base-biased npn transistor in Figure 3–68 , assume βDC = 300. Find IC and VCE. (Hint: The transistor is now saturated!)

FIGURE 3–68

13 .

For the voltage-divider biased circuit in Figure 3–71 , determine IC and VCE.

FIGURE 3–71