Physics EM

posted by .

A battery with EMF 90.0 V has internal resistance R_b = 8.68 Omega.
What is the reading V_v of a voltmeter having total resistance R_v = 485 \Omega when it is placed across the terminals of the battery?
Express your answer with three significant figures.
V_v =88.4V
This is the value I found is correct. I don't see how to solve this next question.

What is the maximum value that the ratio R_b/R_v may have if the percent error in the reading of the EMF of a battery is not to exceed 3.00 %?

  • Physics EM -

    Give up - this question is impossible.

  • Physics EM -

    roflcopter

  • Physics EM -

    Physics2212 students... lets all protest against mastering physics.

  • Physics EM -

    Consider the fractional error as
    a = (V-V_v)/V

    where a is equal to the 0.03 (because in this question the percent error is 3.00%)

    You should know from Kirchhoff's rule that the Electric potential difference is

    V=I(R_b+R_v)

    You also found out that Elec. Poten. diff. with only the voltmeter as resistance is

    V_v =IR_v

    You plug in the Voltage equations to the first equation for the error and play a little with algebra you get the ratio as

    R_b/R_v = (1/(1-a))-1

    Got me the right answer. ;)

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. repost physics E&M please

    A battery with EMF 90.0 V has internal resistance R_b = 8.68 Omega. What is the reading V_v of a voltmeter having total resistance R_v = 485 \Omega when it is placed across the terminals of the battery?
  2. Physics

    A voltmeter of internal resistance of 5000 Ω is connected across the poles of a battery of internal resistance 0.20 Ω. The voltmeter reads 1.4993 volts. What is the actual zero-current emf of the battery?
  3. physics

    when you connect an unknown resistor across the terminals of a 1.50 V AAA battery having a negligible internal resistance, you measure a current of 18.0 mA flowing through it .A)what is the resistance of the resistor. B) if you now …
  4. Physics

    The battery in the circuit diagram has an EMF of 12V and an unknown internal resistance r. Voltmeter V1 is connected across the battery and voltmeter V2 is connected across the switch S. The resistance of the connecting wires and the …
  5. Physics

    The battery in the circuit diagram has an EMF of 12V and an unknown internal resistance r. Voltmeter V1 is connected across the battery and voltmeter V2 is connected across the switch S. The resistance of the connecting wires and the …
  6. physics

    A new "D" battery has an emf of 1.5 V. When a wire of negligible resistance is connected between the terminals of the battery, a current of 25 A is produced. Find the internal resistance of the battery. ________ Ω
  7. physics

    The voltage across the terminals of a 8.90 V battery is 8.00 V when the battery is connected to a 50.0 \Omega load.What is the battery's internal resistance?
  8. PHYSICS

    Two bulbs are connected in parallel across a source of emf EMF = 10.0V with a negligible internal resistance. One bulb has a resistance of 3.0 Omega , and the other is 2.5 Omega . A resistor R is connected in the circuit in series …
  9. physics

    Two bulbs are connected in parallel across a source of emf EMF = 10.0V with a negligible internal resistance. One bulb has a resistance of 3.0 Omega , and the other is 2.5 Omega . A resistor R is connected in the circuit in series …
  10. Physics

    A battery has an internal resistance of 0.42. A number of identical light bulbs, each with a resistance of 31.500, are connected in parallel across the battery terminals. The terminal voltage of the battery is observed to be one-half …

More Similar Questions