Voltage of battery through voltmeter

In summary, the conversation discusses an 85 V battery with an internal resistance of 5.73 ohms. The first question asks for the reading of a voltmeter with a resistance of 482 ohms placed across the battery terminals. The second question asks for the maximum value of the ratio between the battery's internal resistance and the voltmeter's resistance to ensure the error in the reading of the battery's emf does not exceed 5.0%. The solution involves treating the voltmeter as a resistor, finding the current and potential drop across it, and setting a range for the potential drop to meet the error requirement.
  • #1
sebby
5
0

Homework Statement



A 85 V battery has an internal resistance of r = 5.73 ohms .

(a) What is the reading of a voltmeter having a resistance of R_v = 482 ohms when placed across the terminals of the battery?
___________ V
(b) What maximum value may the ratio r/R_v have if the error in the reading of the emf of a battery is not to exceed 5.0%?


Homework Equations



V=IR
V=E-Ir
V_v= I_fs ( R_c +R_s)

The Attempt at a Solution



i don't know where to start, the only thing i have tried was drawing the diagram of the circuit. please offer input on where to start thank you in advance
 
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  • #2
(a) Just treat the voltmeter as a resistor. Then find the current and calculate the potential drop across the voltmeter.

(b) For this let the resistance of the voltmeter be R. Then using the same method above, determine the potential drop across the voltmeter in terms of R, f(R). Then we want 0.95(V)<|f(R)|<1.05(V) where V is the emf of the battery.
 
  • #3
thank you very much i got both answers correct thank you
 

What is voltage?

Voltage is a measure of the electric potential difference between two points in an electric circuit. It is measured in volts (V).

What is a battery?

A battery is a device that converts chemical energy into electrical energy. It consists of one or more cells, which contain positive and negative terminals, or electrodes, that are connected by an electrolyte.

What is a voltmeter?

A voltmeter is a device used to measure the voltage of an electric circuit. It typically consists of a dial or digital display and two probes that are connected to the circuit.

How does a voltmeter measure the voltage of a battery?

A voltmeter is connected in parallel to the battery, meaning that it is connected to the positive and negative terminals of the battery. It measures the potential difference between these two points, which is the voltage of the battery.

Why is it important to measure the voltage of a battery?

Measuring the voltage of a battery is important because it allows us to determine the amount of electrical energy that the battery can provide. It also helps us monitor the health and performance of the battery, and can indicate when it needs to be replaced.

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