# Two batteries with inner resistor in parallel

## Homework Statement:

two batteries A and B are connected in parallel, and an 80 ohm resistor is connected across the battery terminals. the e.m.f and the internal resistance of battery A are 100V and 5ohms respectively, and the corresponding values for battery B are 95V and 3ohms respectively.

## Relevant Equations:

Calculate the value and direction of the current in each battery.
I am kind of stuck at this exercise and I would like some help.

Thanks a lot!

Related Introductory Physics Homework Help News on Phys.org
berkeman
Mentor
Homework Statement: two batteries A and B are connected in parallel, and an 80 ohm resistor is connected across the battery terminals. the e.m.f and the internal resistance of battery A are 100V and 5ohms respectively, and the corresponding values for battery B are 95V and 3ohms respectively.
Homework Equations: Calculate the value and direction of the current in each battery.

I am kind of stuck at this exercise and I would like some help.

Thanks a lot!
Please draw the circuit and show us how you would set up the KCL equations. Thanks

Hi berkeman,

I started to calculate the terminal voltage, cause I thought that might help.
v= terminal voltage

(v/80) + (v-100)/5 + (v-95)/3 =0

v=94.66 V

with that, I calculated the current across the 80 ohm resistor:

I=v/R = 94.66/80 = 1.183

From the answer sheet, I know that this is correct as it is the sum of the individual currents in each battery.
But I do not know how to calculate it. I tried using the current divider rule, but it doesn't work.

#### Attachments

• 42 KB Views: 31
berkeman
Mentor
Ah, sorry, the drawing helps a lot. I thought the resistor was in parallel with the mismatched batteries, so that's why I asked for the KCL equation(s).

Since it is just one loop per the figure, a KVL equation is the better fit. Can you write that equation to see if it helps? The current around the loop through the various components is the same, right?

phinds
• 