30 kΩ 60 kΩ 20 kΩ 20 V

Sample Problems – Solutions Equivalent Circuits (I) 1)

For the circuit shown below, sketch the Thevenin & Norton Equivalent circuits. (Include values for elements in the sketch.)

20 kΩ 20 V

a)

60 kΩ

30 kΩ

Find VOC - Use Voltage Divider VOC = (20 V) (30 kΩ)/(20 + 30)kΩ = 12V

b)

Find ISC - Use voltage divider across equivalent, then find ISC A 20 kΩ 20 V

A

60 kΩ

20 kΩ

I SC

30 kΩ

=>

20 V

B

Reqsc = 30 kΩ || 60 kΩ = 20 kΩ Vreq = VAB = (20 V) (20 kΩ)/(20 + 20) kΩ = 10 V = V30k = V60k ISC = I60k = V60k / 60 kΩ = 1/6 mA c)

Req = VOC/ISC = 12V/(1/6) mA = 72 kΩ

R eqsc = 20 k Ω

B

Check: Turn off source and find Req

20 kΩ V = 0 =>

60 kΩ

60 kΩ