181_Lab_7a

# From the second graph read p max and compare with e 2

This preview shows pages 4–5. Sign up to view the full content.

From the second graph, read P max and compare with E 2 /4r. Read R for P max and compare with r. Equation 2 states that: Additionally, we know that when P is at a maximum, i 2 r=i 2 R From Table 1 we know that Power is at a maximum when R=50 ohms. Therefore, r=50 ohms. Adapting equation 2: And for comparison, using: Our measured value for P max was .0432 Watts, so to find our percent difference: 3) Show that at maximum power output, the terminal voltage of the battery is half its emf. Proven experimentally- We calculated the emf to be equal to 2.88 Volts in part 2. At maximum power output, the terminal voltage was measured at 1.46 Volts.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
.521 is very close to .5 or, one half the emf, and results in a 4.2% error. Proven theoretically- Q1) Why is a dead battery characterized by a high internal resistance? Higher resistances correlate to lower power outputs. Thus meaning, it stands to reason, that when a battery has no more power to offer (is dead), it must have a very high internal resistance. Q2) Explain why batteries of low current capacity have higher internal resistances than those batteries of high current capacity, e.g. a 12v flashlight battery vs. a 12 v car battery. V=IR, where V is the voltage, I is the current capacity, and R is the resistance. Therefore, I and R are inversely proportional. In order to maintain a constant V, 12 volts for instance, as the current capacity gets lower, the resistance must be much higher to compensate. Conclusion: Overall, this lab was a success. The natural behaviors of batteries were all explained, and the relationships between all the variables involved were demonstrated. Additionally, the numerical results that were derived were relatively accurate, with a percentage error just around 4%. The setup for the lab was somewhat complicated, so improvements might come in the form of more explicit directions or a more simplified setup. Otherwise, the lab was successful overall and demonstrated the accuracy of the equations related to emf.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern