Find the voltage across the resistor

A*4082.84Ω which equals 4.45VIn summary, a battery with 12.0 V and internal resistance of 1.0 Ω is connected to two 6.9 kΩ resistors in series. An ammeter with internal resistance of 0.50 Ω measures a current of 1.09 mA. A voltmeter with internal resistance of 10.0 kΩ measures a voltage of 4.45 V across one of the 6.9 kΩ resistors in the circuit.
  • #1
ooohffff
74
1

Homework Statement


A battery with
scriptE.gif
= 12.0 V and internal resistance r = 1.0 Ω is connected to two 6.9 kΩ resistors in series. An ammeter of internal resistance 0.50 Ω measures the current, and at the same time a voltmeter with internal resistance 10.0 kΩ measures the voltage across one of the 6.9 kΩ resistors in the circuit. What do the ammeter and the voltmeter read?

Homework Equations


V=IR

The Attempt at a Solution


So I found the ammeter reading where Itotal=1.09mA which was correct.
For the voltmeter reading, I got:
V=Itotal*6.9kΩ=7.52V which was incorrect. Anyone care to help?
 
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  • #2
ooohffff said:
Anyone care to help?
Help what? You haven't shown any work, just answers. That's not the way it works here.
 
  • #3
phinds said:
Help what? You haven't shown any work, just answers. That's not the way it works here.
Ammeter reading:
Rparallel=[(1/6.9k)+(1/10k)]-1=4082.84
Rtotal= 6.9kΩ+4082.84Ω+1Ω+.5Ω=10984.34Ω
Itotal=V/R=12/10984.34=.00109A

Better?
 
  • #4
Ah, I got it it's V=ItotalRparallel
 

Related to Find the voltage across the resistor

1. What is the purpose of finding the voltage across the resistor?

The purpose of finding the voltage across the resistor is to determine the potential difference between the two ends of the resistor. This is important in understanding the behavior of the resistor in a circuit and how it affects the flow of current.

2. How is the voltage across a resistor calculated?

The voltage across a resistor can be calculated using Ohm's Law, which states that voltage (V) is equal to the product of current (I) and resistance (R). Therefore, V = IR. This formula can also be rearranged to solve for current or resistance.

3. What factors affect the voltage across a resistor?

The voltage across a resistor is affected by the current flowing through it and the resistance of the resistor itself. The voltage can also be affected by the presence of other components in the circuit, such as a power source or other resistors.

4. Can the voltage across a resistor change?

Yes, the voltage across a resistor can change depending on the current and resistance in the circuit. If the current or resistance changes, the voltage across the resistor will also change accordingly.

5. How is the voltage across a resistor measured?

The voltage across a resistor can be measured using a voltmeter, which is a device that is connected in parallel to the resistor in the circuit. The voltmeter measures the potential difference between the two ends of the resistor and displays it in units of volts (V).

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