Problem 1-13: Voltage of A Current Source

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Basic Concepts, Electrical Circuits, Electrical Circuits Problems

Find voltages across the current sources.
a)
A Current Source Parallel with A Voltage Source
b)
Voltage Across Parallel Elements
c)
Parallel Current and Voltage Sources
d)

e)
Parallel Current and Variable Voltage Sources

Solution

In each case, the current source is parallel with a voltage source. Therefore, the voltage across the current source is equal to the voltage of the voltage source, regardless of other elements.

a)
A Current Source Parallel with A Voltage Source
b)
Voltage Across Parallel Elements

c)
Parallel Current and Voltage Sources

d)
Parallel Current and Voltage Sources
e)
Parallel Current and Variable Voltage Sources

Current Source Independent Sources

Comments

12 responses to “Problem 1-13: Voltage of A Current Source”

February 18, 2012

Chris Cole

Dr. Li –

I am trying to understand circuit d better. Why is it that the 6 ohm resister doesn’t conduct? What direction does the current flow through the battery? Can it be redrawn in a way making it clearer?

Thank you.

Reply
1. February 18, 2012
  
  Dr. Yaz Z. Li
  
  The $6 \Omega$ is short circuited. Then the all portion of current passes through the wire which is short circuiting the $6 \Omega$ . When two sides of a resistor are connected to each other, the voltage across the resistor is zero. Therefore, the Ohm’s law also implies that the current is zero: $V=RI=0 \to I=0$ .
  The current of $3 \Omega$ is $\frac{3V}{3 \Omega}=1 A$ from the top to the bottom. The current of the current source is $2 A$ from the top to the bottom. So, the current of the voltage source is $2 A + 1 A$ from bottom to the top, i.e. from the negative terminal to the positive one.
  
  Reply
March 3, 2012

wngzo

thanks alot for sharing your knowledge with us….
do me a favor?
what is meant by
1) voltage controlled current source and
2) current controlled voltage source ,
3)voltage controlled voltage source and also
4) current controlled current source?

Reply
1. August 24, 2013
  
  samtopper
  
  sir i want clarity among the four sources.
  1) voltage controlled current source and
  2) current controlled voltage source
  3)voltage controlled voltage source and
  4) current controlled current source.
  
  Reply
May 18, 2012

k.madhu

in these given circuit howcan we find which source is supplying and which source is obsorbing or both are suppling power

Reply
May 18, 2012

k.madhu

what is the cirrent through 2v battary of circuit (b)

Reply
1. September 15, 2014
  
  priya
  
  Current through 2v battery is 4.8 A
  
  Reply
November 19, 2013

nadeem

thanks alot for sharing your knowledge with us….
do me a favor?
what is meant by
1) voltage controlled current source and
2) current controlled voltage source ,
3)voltage controlled voltage source and also
4) current controlled current source?

Reply
1. November 19, 2013
  
  Yaz
  
  1) voltage controlled current source
  It is a current source whose current is related to a voltage drop somewhere. For example:
  
  The current source at right side bottom is a voltage controlled current source. So, it is a current source but instead of having a constant current value, it is current is always two times of the voltage drop across the $2\Omega$ at top left ( $2 V_y$ ).
  
  A very similar definition for the other three sources. Let me know if you need more explanations.
  
  Reply
September 30, 2014

Toba

Can the voltage across a dependent current source be zero?

Reply
1. September 30, 2014
  
  Yaz
  
  Yes, it can. Like independent current sources, voltage across dependent current sources can be any value. If you connect two nodes of a dependent current source, the voltage across it is zero.
  
  Reply
November 17, 2014

rishan

can i know the superposition theory in problems with solution

Reply