UNIT-19: Potentiometer, PRE-LAB Name: ID# This pre-lab is worth 5 points Course#

Question

UNIT-19: Potentiometer, PRE-LAB Name: ID# This pre-lab is worth 5 points Course# 14 Section 1) A potentiometer measures the of the cell. From equation [ drawn from the cell, what will happen to the terminal voltage, Vr? 2) if the internal resistance, r, and emf, , is constant, as more current, I, is 3) From procedure Part B, when an external resistance Ru loads an EMF source and when Ri is equal to the internal resistance of the cell, f, (i.e., Ru-r), What is the terminal voltage, V, in terms of the emf source, ? 4) Write an equation to determine the terminal voltage of a cell, Vi using the terms Lad, Lt, and

Explanation / Answer

Solution:

Let us go to the basics first.

Answer(1): We know that, a potentiometer is an instrument for measuring voltage by comparison of an unknown voltage with a known reference voltage.

Thus, answer (1) ===> A potentiometer measures the voltage of the cell.

Answer (2): Equation [1] not provided.

Answer (3): I = emf / (RL + r)

=> I = / (RL + r)

We know that terminal voltage, VT = IRL

=>  VT = RL / (RL + r)

=> VT = r / (r + r) [given, r = RL ]

=> VT = / 2 [Answer 3] thus, Terminal voltage is half of emf source voltage.

Thanks!!!

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