Calculating current in series circuit

[tweety1234]

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?

 

[Doc Al]

You're given all the information needed to calculate the current.

 

[tweety1234]

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?

 

[Doc Al]

okay so would it be like this ;

6/ 10 = 0.6 Amps

No. What's the total resistance in the circuit?

 

[tweety1234]

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?

 

[tweety1234]

oh i got it now , was suppose to multiply by 10 instead of 0.4

thanks for the help

 

[Doc Al]

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?)