Which component is used to measure the potential difference $V$ across a branch in an electric circuit?

A circuit consists of a battery connected to a resistor of resistance $R$. If a current $I$ flows through the resistor, what is the voltage of the battery?

A circuit consists of an ideal battery with emf $e$ connected directly to an ideal voltmeter. What is the reading $V$ of the voltmeter? Express your answer in terms of the emf $e$.

A circuit consists of an ideal battery with emf $e$ connected directly across an ideal voltmeter. What is the reading $V$ of the voltmeter? Express your answer in terms of the emf $e$.

Which of the following best defines voltage in the context of electric potential?

A voltmeter is used to test which of the following quantities in an electric circuit?

A volt is a unit of electric:$V$

A circuit consists of a battery with emf $e$ and internal resistance $r_{\mathrm{int}}$ connected in series with an external resistor $r$. What is the reading of the ammeter (current $i$) in terms of $e$, $r$, and $r_{\mathrm{int}}$?