Final answer:
To calculate the voltage drop across a resistor, use Ohm's Law (V=IR). For the given example with a 10 ohm resistor and 0.025 A current, the voltage drop is 250 mV (or 0.25 V). A voltmeter measures potential differences by connecting in parallel across components.
Step-by-step explanation:
Understanding Current and Voltage in Circuits
The question seems to involve measurements of voltage and current across electrical components. To address the question about the voltage drop across a resistor given the current, Ohm's Law is used, which states that the voltage (V) across a resistor is equal to the product of the current (I) flowing through it and its resistance (R). So, for a 10 ohm resistor with 0.025 A of current, the voltage drop is V = I * R, which equals 0.025 A * 10 ohm, or 0.25 V, which is 250 mV. In terms of measuring voltage in different parts of a circuit, a voltmeter is connected in parallel across the component you need to measure the potential difference for. Calculating the terminal voltage of a battery requires knowledge of both the electromotive force (emf) of the cell and the internal resistance, as well as the resistance of the voltmeter used.