Calculate the emf of Battery w/ External & Internal Resistance

In summary, to find the emf of the battery shown, we use the equations V=Ir and V= E +/- IR, where V represents voltage, I represents current, and R represents resistance. Since the current is flowing away from the battery, we use the equation V= E - Ir. Plugging in the values of 4.0 A for current and 2.50 ohm for external resistance, we find that the voltage of the whole battery is 10V. To find the emf, we use the equation E= V + Ir and plug in the values of 10V for V and 0.5 ohm for internal resistance, resulting in an emf of 12V.
  • #1
Jabababa
52
0

Homework Statement


What is the emf of the battery shown?

there is an external resistance of 2.50 ohm and 4.0 A...The battery has an internal resistance of 0.50ohm

Homework Equations



V=Ir
V= E +/- IR


The Attempt at a Solution



Since the current is going away the battery then i use the equation V= E - Ir
To find the V of the whole battery V= IR, V=(4)(2.5) = 10V
E= V + Ir
E= 10 + (4)(0.5) = 12 V

please check see if its right. If I am not clear i can upload a picture.
 
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  • #2
Jabababa said:

Homework Statement


What is the emf of the battery shown?

there is an external resistance of 2.50 ohm and 4.0 A...The battery has an internal resistance of 0.50ohm

Homework Equations



V=Ir
V= E +/- IR


The Attempt at a Solution



Since the current is going away the battery then i use the equation V= E - Ir
To find the V of the whole battery V= IR, V=(4)(2.5) = 10V
E= V + Ir
E= 10 + (4)(0.5) = 12 V

please check see if its right. If I am not clear i can upload a picture.

Again your logic appears good - unless the diagram is quite unusual.
 

FAQ: Calculate the emf of Battery w/ External & Internal Resistance

What is the formula for calculating the emf of a battery with external and internal resistance?

The formula for calculating the emf of a battery with external and internal resistance is:
EMF = E0 - I(Rint + Rext)

How do I determine the internal resistance of a battery?

The internal resistance of a battery can be determined by measuring the voltage drop across a known load and using Ohm's law (R = V/I) to calculate the resistance. This can be done for multiple loads and the average resistance can be used as the internal resistance.

What is the significance of the internal resistance in calculating emf?

The internal resistance affects the flow of current in the circuit and can cause a voltage drop, resulting in a lower emf than the theoretical value. It also determines the maximum current that the battery can supply.

How does the external resistance affect the emf of a battery?

The external resistance also determines the flow of current in the circuit and can cause a voltage drop. The larger the external resistance, the lower the current and the higher the voltage drop, resulting in a lower emf.

Can the emf of a battery change over time?

Yes, the emf of a battery can change over time due to factors such as temperature, age, and usage. External factors such as connecting multiple batteries in series or parallel can also affect the overall emf of the system.

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