Experiment to find out emf of the battery

In summary, the conversation discusses an experiment conducted to measure the emf of a battery. The result was 1.35 volts, which is lower than the labeled voltage of 1.5 volts. The conversation suggests that this difference may be due to the battery being old and losing voltage over time. Different methods were used to measure the voltage, but all gave a similar result. The conversation also mentions the importance of understanding the discharge curve of batteries and provides an example of discharge curves for AA alkaline batteries from different manufacturers.
  • #1
Gajan1234
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I conducted an experiment to find out the emf of a battery, the result turned out to be 1.35 volts , however on the battery, it says the battery is 1.5 voltage.

Does it mean that my method is wrong or less accurate. But I used three different methods:1) measuring the terminal voltage across the battery when there is no current going through the battery

2) Measuring the voltage when the current changes and then ploting the graph to finf the y intercept

3) using the formula r= V1-V2/I2-I1

All of those method gave me approximately 1.35 volts.
 
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  • #2
Hi Gajan:

Batteries tend to lose their voltage as they are used over time. Therefore an old battery may fail to have the voltage it had when it was new. Do you have a brand new battery you can test?

Regards,
Buzz
 
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  • #3
It makes much more sense, I didnt think in that way and yh I did use a old battery so it makes sense
 
  • #4
It is good to understand the discharge curve for any battery you are studying or experimenting with. For example for an AA alkaline, here is are some typical discharge curves for batteries from different manufacturers ( for example RS = radio shack) (from http://www.powerstream.com/AA-tests.htm)

AA-500mA.png


The curves will be different for different currents. The Amp Hours (AH) rating is always at a specific constant discharge current.
 
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Related to Experiment to find out emf of the battery

1. What is the purpose of an experiment to find out the EMF of a battery?

The purpose of this experiment is to determine the electromotive force (EMF) of a battery, which is a measure of the battery's ability to supply an electric current. This information can be useful in understanding the battery's performance and comparing it to other batteries.

2. What materials are needed for this experiment?

The materials needed for this experiment include a battery, a voltmeter, a resistor, and connecting wires. The resistor is necessary to create a circuit and the voltmeter is used to measure the voltage. It is also important to use a resistor with a known resistance value to accurately calculate the EMF.

3. How do you set up the experiment to find out the EMF of a battery?

To set up the experiment, connect the positive terminal of the battery to one end of the resistor and the negative terminal to one end of the voltmeter. Then, connect the other end of the resistor to the other end of the voltmeter. This creates a circuit with the resistor and voltmeter in series. Make sure all connections are secure and the voltmeter is set to measure DC voltage.

4. What is the procedure for conducting the experiment?

Once the setup is complete, turn on the voltmeter and record the voltage reading. This is the potential difference across the resistor, which is equal to the EMF of the battery. To get a more accurate measurement, the experiment can be repeated multiple times and the average of the readings can be calculated.

5. How is the EMF of the battery calculated from the experiment?

The EMF of the battery is calculated by using Ohm's Law, which states that the voltage (V) is equal to the product of the current (I) and resistance (R). Therefore, EMF = V/I. In this experiment, the current can be calculated by dividing the voltage reading by the resistance value of the resistor. Substituting this value into the equation gives the EMF of the battery.

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