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Chapter 21: Q57PE (page 777)

What is the emfxof a cell being measured in a potentiometer, if the standard cell’s emf is 12.0 Vand the potentiometer balances forRx=5.000Ωand Rs=2.500Ω?

Short Answer

Expert verified

The of a cell being measured in a potentiometer is Ex=24.0V.

Step by step solution

01

Concept Introduction

The electric potential generated by an electrochemical cell or a changing magnetic field is known as electromotive force. Electromotive force (EMF) is a well-known abbreviation.

02

Information Provided

  • Emf of a standard cell: Es=12V
  • Resistance of the potentiometer:Rx=5Ω
  • Standard resistance value:Rs=2.5Ω
03

Calculation for EMF of the cell

Calculate emfx, of a cell using a potentiometer. The formula is -

Ex=EsRxRs=(12V)5Ω2.5Ω=12V×2.0=24.0V

Therefore, the value for emf is Ex=24.0V.

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Most popular questions from this chapter

An 1800-W toaster, a 1400-Welectric frying pan, and a75-Wlamp are plugged into the same outlet in a15A,120Vcircuit. (The three devices are in parallel when plugged into the same socket.) (a) What current is drawn by each device? (b) Will this combination blow the 15-A fuse?

What is the sensitivity of the galvanometer (that is, what current gives a full-scale deflection) inside a voltmeter that has a1.00‐MΩresistance on its30.0‐Vscale?

Knowing that the severity of a shock depends on the magnitude of the current through your body, would you prefer to be in series or parallel with a resistance, such as the heating element of a toaster, if shocked by it? Explain.

The label on a portable radio recommends the use of rechargeable nickel-cadmium cells (nicads), although they have a 1.25-V emf while alkaline cells have a 1.58-V emf. The radio has a 3.20-Ω resistance.(a) Draw a circuit diagram of the radio and its batteries. Now, calculate the power delivered to the radio. (b) When using Nicad cells each having an internal resistance of 0.0400 Ω.(c) When using alkaline cells each having an internal resistance of 0.200 Ω.(d) Does this difference seem significant, considering that the radio’s effective resistance is lowered when its volume is turned up?

Specify the points to which you could connect a voltmeter to measure the following potential differences in Figure \(21.49\): (a) the potential difference of the voltage source; (b) the potential difference across \({R_1}\) ; (c) across \({R_2}\) ; (d) across \({R_3}\) ; (e) across \({R_2}\) and \({R_3}\) . Note that there may be more than one answer to each part.
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