Calculating current in series circuit

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Homework Help Overview

The discussion revolves around calculating the current in a series circuit and determining the voltage when a switch is closed. The original poster expresses confusion about how to find the voltage without knowing the current, despite having a specific answer in mind.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between voltage, current, and resistance, referencing Ohm's law. There are attempts to calculate current based on given values, and questions arise about the inclusion of internal resistance in the calculations.

Discussion Status

The discussion is active, with participants providing guidance and questioning assumptions about the circuit's parameters. Some participants have made calculations, while others are clarifying the implications of internal resistance and its effect on the voltage reading across the battery terminals.

Contextual Notes

There is mention of specific values for voltage and resistance, as well as the internal resistance of the battery, which may influence the calculations. The original poster's reference to a specific answer suggests a potential misunderstanding of the problem setup.

tweety1234
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Homework Statement



can anyone please guide me on how to do question 3b? I don't seem to get the right answer. how do i calculate the voltage when the switch is closed if i don't know what the current is?

btw the right answer is 5.77 volts


Homework Equations



v=IR?
 

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You're given all the information needed to calculate the current.
 
Doc Al said:
You're given all the information needed to calculate the current.

okay so would it be like this ;

6/ 10 = 0.6 Amps

but can this value be used for the calculation when the switch is closed?
 
tweety1234 said:
okay so would it be like this ;

6/ 10 = 0.6 Amps
No. What's the total resistance in the circuit?
 
Doc Al said:
No. What's the total resistance in the circuit?

oh right, but i thought you don't include the internal resistance of the battery if the switch is open ?

6/10.4 = 0.577

0.577 x 0.4 = 0.23 volts

? is this correct?
 
Last edited:
oh i got it now , was suppose to multiply by 10 instead of 0.4

thanks for the help
 
tweety1234 said:
oh right, but i thought you don't include the internal resistance of the battery if the switch is open ?
This problem asks for the voltmeter reading when the switched is closed.

6/10.4 = 0.577
That's the current.

0577 x 0.4 = 0.23 volts
That's the voltage drop due to the internal resistance. But what's the full voltage reading across the battery terminals? (Does that 0.23 volts add or subtract from the battery's emf?)
 

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