Question

What is the total voltage supplied by the battery? (must include unit - V)

Answer 1

`\rm 100\; V`.

Step-by-step explanation:

The battery here is connected to three resistors. Because these resistors are connected in series:

• the voltage supplied by the battery is the sum of the voltage across each of the three resistors.
• the current across the three resistors is the same.

The voltmeter on the right reads
`20\; \rm V`. Since this voltmeter is connected in parallel with
`R_2`, it measures the voltage across

The voltage across
`R_1` and
`R_3` can be found with Ohm's Law. Note that the ammeter on the lower-right corner reads
`2\; \rm A`. Because this circuit is connected in series, the current through each of its three resistors in would all be

• 
  `R_1 = 15\; \Omega`.
  `I_1 = 2\; \rm A`. By Ohm's Law,
  `V_1 = I_1 \cdot R_1 = 2\; \rm A * 15 \; \Omega = 30\; \rm V`.
• 
  `R_3 = 25\; \Omega`,
  `I_3 = 2\; \rm A`. By Ohm's Law,
  `V_3 = I_3\cdot R_3 = 2\; \rm A * 25\; \rm \Omega = 50\; \rm V`.

Since the three resistors are connected in series:

`\begin{aligned}& V(\text{from battery})\\ &= V(\text{across circuit}) \\ &= V_1 + V_2 + V_3 \\&= \rm 30\; V + 20 \; V + 50 \; V \\&= 100\; \rm V\end{aligned}`.