Why Does a Slide-Wire Potentiometer Require a Higher Voltage Battery?

AI Thread Summary
A slide-wire potentiometer requires a higher voltage battery, typically greater than 2 volts, to ensure accurate measurements of electromotive force (emf) without significant error. The polarity of the galvanometer is unimportant because it measures current flow rather than voltage direction. A rheostat functions as a variable resistor to control current, while a galvanometer indicates the presence and direction of current. A voltmeter is more desirable than a potentiometer when measuring voltages in circuits with rapidly changing conditions. To demonstrate that a potentiometer measures the emf of a test cell rather than its terminal potential difference (TPD), one should explore the relationship between the circuit components and the principles behind emf measurement.
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need everyone's help... pls. explain it to me for those who knows the experiment...thanks!

1) in measuring emf by slide-wire potentiometer, why should the working battery have a voltage greater than 2? why is the galvanometer polarity unimportant?
2)how is the function of a rheostat different from a galvanometer?
3)under what condition is a voltmeter more desirable than apotentiometer for the measurement of voltages?
lastly,
4)how can i prove that the potentiometer measures the emf of the test cell and not its TPD? where do i start in solving this?

guys, pls. help. physics really kills me. really not good in physics i guess...
 
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I would love to answer, but I'm afraid you will be learning little from direct answers. I'm sure you will be getting them from your instructor anyway. It even looks as if you didn't take much effort to answer some of the very obvious questions and pasted your homework questions directly. You should think about them carefully. Does a resistor have polarity (does it matter which way goes to the positive side or negative?). How does a galvanometer work? (Hint, its related to current). Do you know what a rheostat is? A potentiometer?
 
sorry coz' i didn't understand my teacher so i thought i could get better explanations here. it's ok if those are only direct answers, it may help anyways.. thank u for the reply. other answers are still welcome.
 
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