Which instrument is used to measure the power in an electric circuit?

The instrument used to measure power in an electric circuit is called a wattmeter. Electrical power represents the rate at which energy is consumed or produced in a circuit, and it is measured in watts (W). Power can be calculated as the product of voltage and current in a circuit, often expressed as P = V × I, where P is power, V is voltage, and I is current.

A wattmeter is specifically designed to measure this electrical power directly. It typically consists of two coils: a current coil connected in series with the load, and a voltage coil connected in parallel across the circuit. When current flows through the current coil and voltage is applied across the voltage coil, the interaction of the magnetic fields produces a deflection on the meter’s pointer, indicating the power in watts.

Other instruments listed, like a wavemeter, are used to measure the frequency of electromagnetic waves, while a viscometer is used in fluid mechanics to measure the viscosity of liquids. These instruments are unrelated to electrical power measurement.

Understanding how a wattmeter works is important in Physics, especially in electric circuits, electrical engineering, and applied electronics. It helps students measure energy consumption in household devices, industrial machinery, and electronic circuits accurately. Modern wattmeters may be analog or digital, but the principle remains the same—measuring the instantaneous power in a circuit using the interaction of voltage and current.

By using a wattmeter, one can not only monitor energy usage but also ensure the safe and efficient operation of electrical systems. It is a fundamental tool for both students learning electricity and professionals working with electrical devices.