Question

Consider the circuit shown below. All three batteries are ideal. The voltmeter and ammeter are also ideal. 7.00V 崇弓= 12.0V v) R 5.00 R2 6.00 Ω = 8.00 V A. What is the internal resistance of the batteries? B. What is the internal resistance of the voltmeter? C. what is the internal resistance of the ammeter? D. Based on your answers to questions A-C draw a simpler equivalent circuit (in the space above to the right of the original circuit) in which the voltmeter and ammeter are replaced with equivalent elements in keeping with their ideal nature. You are required to solve E and F by using Kirchoff's Voltage and Current Laws to generate loop and junction equations that can be used to determine the answers What does the voltmeter read? (If the potential at point a is greater than point b report a positive result. If the potential at point b is greater than point a report a negative result.) E. What does the ammeter read? (If conventional flow through the ammeter is toward the top of the page, report a positive result. If conventional flow through the ammeter is toward the bottom of the page, report a negative result.) F. G. If we define the potential at point b to be 0 V, label the potentials at all the other points (a-g).

Answer 1

[A] Ideal batteries have 0 internal resistance.

[B] Ideal voltmeter have infinite internal resistance.

[C] Ideal ammeter have 0 internal resistance.

[D]

7V 5.0 gy

[E]

Voltage law in abcg.

$V_a=V_b+8+7=V_b+15$

$\textup{Voltmeter reading }=\Delta V_{ab}=V_a-V_b=15\textup{ V}$

[F] Current in branch ab

$i_{a\to b}=\frac{15}{5}=3\textup{ Amp}$

Voltage law in cdfg, if the current in branch fd is $i_{f\to d}$

$12-6i_{f\to d}=0\Rightarrow i_{f\to d}=2\textup{ Amp}$

Current law at point c,

$i_{f\to d}+i_{a\to b}=i_{c\to g}$

$\Rightarrow i_{c\to g}=5\textup{ Amp}$

[G]

$\begin{align*} V_b=0\textup{ V}\\ V_c=8\textup{ V}\\ V_d=8\textup{ V}\\ V_g=8\textup{ V}\\ V_f=8\textup{ V}\\ V_a=15\textup{ V}\\ \end{align*}$