Circuit with 2 batteries is confusing me

In summary: That's not the answer to the question.In summary, the voltage difference between points a and b in the circuit is 1.421V due to the voltage drop across R3. The equivalent resistance between points a and b is 2 ohms, and the total current in the circuit is 0.286A. The correct answer to the question is the voltage drop of 0.579V across points a and b.
  • #1
mujadeo
103
0

Homework Statement


The circuit in the figure is composed of two batteries (E1 = 6 V and E2 = 4 V) and three resistors (R1 = 4 , R2 = 4 , R3 = 5 ) as shown.

(a) What is the current I3 flowing through the batteries?

I3 = .286A (no problem here)

(b) What is the voltage Vb - Va between the points a and b in the circuit?

Vb - Va = V

So i combined the parallel Rs to get R1 + R2 = 2ohms
So voltage in is 2V right?
Then voltage on other side of Req should be .579V right? (because I=.286A)
so then 2V - .579V = 1.43 = wrong answer
please help!

thanks


Homework Equations





The Attempt at a Solution


 

Attachments

  • showme2.gif
    showme2.gif
    2 KB · Views: 505
Physics news on Phys.org
  • #2
mujadeo said:
(b) What is the voltage Vb - Va between the points a and b in the circuit?

Vb - Va = V

So i combined the parallel Rs to get R1 + R2 = 2ohms
Good.
So voltage in is 2V right?
How did you deduce this? You have the resistance and the current.
Then voltage on other side of Req should be .579V right? (because I=.286A)
Do you mean the voltage across R3? What's the current through R3?
 
  • #3
because picture says current is going cw, so 1st batt is -4V and 2nd batt is 6V = 2V
so 2V enters Req.
Req = 2ohms
and total current in the circuit is .286A
so V=IR = .286 X 2ohm = .579V
2V - .579V = 1.421V
 
  • #4
Much better. (Unless the reference point is very clear, it's always a good idea to specify the voltage difference between two points or across something.)
 
  • #5
1.421V is wrong answer though, so can u please tell me what I am doing wrong?
thanks
 
  • #6
You did the work correctly, but you're getting confused about which voltage drop is the answer to the question.
mujadeo said:
because picture says current is going cw, so 1st batt is -4V and 2nd batt is 6V = 2V
so 2V enters Req.
Req = 2ohms
This is the equivalent resistance between points A and B.
and total current in the circuit is .286A
This is the total current going through both R3 and between points A and B.
so V=IR = .286 X 2ohm = .579V
That's the voltage drop across A and B. That's the answer to the question.
2V - .579V = 1.421V
That's the voltage across R3.
 

What is a circuit with 2 batteries?

A circuit with 2 batteries is a closed loop of electrical components that allows for the flow of electricity between the positive and negative terminals of two batteries. This creates a continuous flow of electricity, powering the components connected in the circuit.

How does a circuit with 2 batteries work?

In a circuit with 2 batteries, the positive terminal of one battery is connected to the negative terminal of the other battery, creating a larger voltage difference between the two ends of the circuit. This increased voltage allows for more energy to flow through the circuit, powering the connected components.

What are the advantages of using a circuit with 2 batteries?

Using 2 batteries in a circuit can provide a higher voltage output, allowing for more energy to be delivered to the connected components. This can be useful for powering larger or more energy-intensive devices.

Can I use any type of battery in a circuit with 2 batteries?

It is important to use batteries with the same voltage and capacity in a circuit with 2 batteries. This ensures that the batteries will discharge at the same rate and prevent damage to the circuit or batteries. It is also recommended to use batteries of the same brand and type to ensure consistency.

What are some safety precautions to keep in mind when working with a circuit with 2 batteries?

Always use caution when working with electricity. Make sure to disconnect the batteries when not in use and avoid touching the terminals with bare hands. It is also important to properly dispose of batteries when they are no longer usable and never mix old and new batteries in a circuit.

Similar threads

Circuit analysis: Six resistors and two batteries
    • Introductory Physics Homework Help
Replies
1
Views
1K
Power dissipated in this circuit with 2 batteries and 3 resistors
    • Introductory Physics Homework Help
Replies
22
Views
2K
Solving series-parallel circuits
    • Introductory Physics Homework Help
Replies
1
Views
849
Single Loop Potential difference -- sign issue
    • Introductory Physics Homework Help
Replies
8
Views
699
How to solve this chain with Kirchhoff's laws?
    • Introductory Physics Homework Help
Replies
18
Views
2K
Circuit is constructed with six resistors and two batteries
    • Introductory Physics Homework Help
Replies
2
Views
1K
Finding the Current in a Resistor in a Closed Circuit
    • Introductory Physics Homework Help
Replies
4
Views
2K
What is the potential at the top of R2 in this circuit?
    • Introductory Physics Homework Help
Replies
16
Views
3K
Find currents and voltages - 2 batteries & 3 resistors
    • Introductory Physics Homework Help
Replies
3
Views
3K
The equivalent resistance for the resistors in this circuit?
    • Introductory Physics Homework Help
Replies
5
Views
1K

Hot Threads

Recent Insights

Back
Top