Understanding Odometer Measurement

The question asks about the measurement taken by a device called an 'odometer'. An odometer is a common instrument found in vehicles.

What an Odometer Measures

An odometer is specifically designed to measure the distance traveled by a vehicle, such as a car, motorcycle, or bicycle. It counts the rotations of a wheel or uses electronic sensors to calculate the total distance covered from a starting point (usually the vehicle's origin or a trip reset point).

• The main function of an odometer is to record the cumulative distance covered over time.
• This distance is typically displayed on the dashboard of a vehicle, often in miles or kilometers.

Analyzing the Options

Let's look at the given options:

• Electric energy: Electric energy is typically measured in units like kilowatt-hours (kWh) using devices like energy meters. An odometer does not measure electric energy.
• Radioactivity: Radioactivity is measured using devices like Geiger counters or scintillators, often in units like Becquerels (Bq) or Curies (Ci). An odometer has no function related to measuring radioactivity.
• Distance covered: As explained, an odometer is the standard instrument used to measure the distance covered by a vehicle.
• The speed of an aeroplane: Speed is measured using devices like speedometers or airspeed indicators (for aircraft). While distance and time are related to speed, an odometer directly measures distance, not instantaneous or average speed.

Based on the function of an odometer, the quantity it measures is the distance covered.