Electric Circuts (Voltage, Ohms, Amps)

In summary, the conversation discusses solving a problem involving unknown values for R3 and R4. The speaker suggests using equations with R3 as the independent variable and determines that the voltage across R2 and the current through the chain can be used to find the voltage across R4 and R3. The conversation ends with a question about using Ohm's Law to find the voltage across R4.
  • #1
Kmcquiggan
29
1
Homework Statement
Examine circuit and complete table and determine the power of the circuit.
Relevant Equations
v_1= I_1 R_1,I_3=I_4= I_T-I_2,R_T= V_T/I_T
246044


I made a chart and this is my attempt. I am not sure that I am doing the calculations right thou

246045
 
Physics news on Phys.org
  • #2
(1) Since there is no value for r3, the problem is unsolvable except as equations using r3 as the independent variable
(2) Show your work (I'm assuming YOU have a value for r3)
 
  • #3
No there is no value for R3
 
  • #4
Kmcquiggan said:
No there is no value for R3
Then your answers are all bogus.
 
  • #5
I was assuming because R3 and R4 are parallel that the values would be the same.
 
  • #6
Kmcquiggan said:
I was assuming because R3 and R4 are parallel that the values would be the same.
r3 and r4 are NOT in parallel, they are in series and there is zero reason to assume they have the same value whether they are series or parallel.
 
  • #7
Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find
 
  • #8
Kmcquiggan said:
Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find
As I have already said, it IS solvable, it's just that the answers will be equations using r3 as the independent variable
 
  • #9
Kmcquiggan said:
Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find
You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.
 
  • #10
ehild said:
You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.
Good catch. I didn't even see the amperage figures. o:)
 
  • #11
phinds said:
Good catch. I didn't even see the amperage figures. o:)
I was wondering!
OP: I believe you did everything correct except your assumption about R3 and therefore the voltage across it. Did you do the table like "cross word puzzle" or did you write down equations?. Either way is fine but learn to do both!
 
  • #12
I wrote down the equations and did them one by one on a scrap piece of paper. And thank you for the help :)
 
  • #13
ehild said:
You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.
I am lost on how to find this. I was multiplying the resistance by the current? I am assuming that is not the formula
 
  • #14
Kmcquiggan said:
I am lost on how to find this. I was multiplying the resistance by the current? I am assuming that is not the formula
Why not?
Do you know Ohm's Law? The current through R4 is 0.06 A, The resistance R4 is 12 ohm. So what is the voltage across R4?
 

FAQ: Electric Circuts (Voltage, Ohms, Amps)

What is the definition of voltage?

Voltage is the measure of the potential energy difference between two points in an electric circuit. It is commonly referred to as the force that pushes electrons through a circuit.

How is voltage measured?

Voltage is measured using a device called a voltmeter, which is connected in parallel to the circuit. The unit of measurement for voltage is volts (V).

What is the relationship between voltage, current, and resistance?

According to Ohm's Law, voltage (V) is equal to the product of current (I) and resistance (R). This can be represented by the equation V = IR. In other words, as voltage increases, current also increases, but as resistance increases, current decreases.

What is the difference between direct current (DC) and alternating current (AC)?

Direct current flows in one direction only, while alternating current alternates between flowing in one direction and then the other. DC is commonly used in batteries, while AC is used in the power grid and household outlets.

How are amps and watts related?

Amps (A) and watts (W) are both units of measurement for electrical current. Watts are calculated by multiplying amps by volts (W = VA), and represent the amount of power being used in a circuit.

Similar threads

Ohm's Law - Finding Source Voltage
Replies
3
Views
1K
Ohm's law and Kirchoff — What am I missing?
Replies
4
Views
1K
Understanding Back EMF in Electric Motors
Replies
19
Views
2K
What Current Flows in a Coil at 230V, 50Hz?
Replies
5
Views
2K
Circuit Problem -- Combining 4 resistors to make 95 Ohms
Replies
10
Views
2K
Incandescent Bulb - suitable approximation for voltage-current curve
Replies
2
Views
467
Calculate the individual voltage, current and power in series and para
Replies
1
Views
1K
I am having some difficulties solving a combination circuits problem
Replies
13
Views
1K
Electric current flowing in a power transmission line
Replies
16
Views
2K
Find the resistance and EMF in a circuit
Replies
15
Views
2K

Hot Threads

Recent Insights

Back
Top