One day, Xiao Ming found that an old incandescent lamp marked "220 V & nbsp; & nbsp; 40 W" was dim. He ran to the corridor to observe the electric energy meter, and measured the electric power of 1200 W with his watch. (1) "it can't be the electric power of the incandescent lamp!" Xiaoming checked that the reading and calculation were correct, and the watt hour meter and watch were accurate. With the help of his father, the voltage at both ends of the incandescent lamp was measured to be 220 v. please analyze the cause of this error______ (2) after analyzing the cause and correcting the error, Xiao Ming measured again that the electric power of this lamp is 36W. The reason why the actual power of the incandescent lamp is lower than the rated power is that______ ．

One day, Xiao Ming found that an old incandescent lamp marked "220 V & nbsp; & nbsp; 40 W" was dim. He ran to the corridor to observe the electric energy meter, and measured the electric power of 1200 W with his watch. (1) "it can't be the electric power of the incandescent lamp!" Xiaoming checked that the reading and calculation were correct, and the watt hour meter and watch were accurate. With the help of his father, the voltage at both ends of the incandescent lamp was measured to be 220 v. please analyze the cause of this error______ (2) after analyzing the cause and correcting the error, Xiao Ming measured again that the electric power of this lamp is 36W. The reason why the actual power of the incandescent lamp is lower than the rated power is that______ ．

(1) The measured power is much higher than the rated power. It is certain that there are other electrical appliances at home. (2) after the incandescent lamp is used for a long time, the tungsten wire will sublimate, making the filament thinner and the cross-sectional area smaller, causing the resistance to increase and the actual power to decrease

What is the purpose of repeated measurement in the experiment of measuring the electric power of light bulb?

The measurement error can be reduced by averaging multiple measurements

Why is watt a unit of electric power?

In 1776, the first steam engine with practical value was manufactured. After a series of major improvements, it became the "universal prime mover" and was widely used in industry. He opened up a new era of human energy utilization, marking the beginning of the industrial revolution. In memory of this great inventor, later generations set the unit of power as "watt"

How to express electric power beyond watt
What does KVA mean?

DC circuit, the unit of power is Watt, and kilowatt
The essence of W is voltage * current (V * a)
AC power grid, AC power is called KVA (including active and reactive)
As for why it is so stipulated, I will know later when I learn alternating current
Word limit, a few words not clear, sorry