Which quantity cannot be measured directly from an oscilloscope?

The correct answer is resistance. An oscilloscope is designed primarily for the visualization of electronic signals over time, allowing for the measurement of voltage, current (in some configurations), and frequency by analyzing the shape and properties of waveforms displayed on its screen.

Voltage can be measured directly by connecting the oscilloscope probes across a component or circuit point, where the oscilloscope translates the voltage levels into a graphical representation.

Current can also be measured indirectly by using a current probe or by measuring the voltage across a known resistor (ohm) according to Ohm’s Law. This allows for calculating the current based on the measured voltage.

Frequency is determined by analyzing the waveform’s characteristics, such as the time period between cycles, which can be visually measured on the oscilloscope.

In contrast, resistance cannot be measured directly with an oscilloscope because it requires a different method, typically using a multimeter. Resistance measurement involves applying a known voltage and measuring the current flowing through a component, which cannot be performed with an oscilloscope alone. Thus, while an oscilloscope is an invaluable tool for various measurements in electronics, measuring resistance is not one of its direct capabilities.