The first Wh, full name Watt-hour, is a physical term, a unit of electric energy, and a quantity proportional to voltage, current and time.

For example, if it is 4.2V, it can be said that the relationship between the discharge time and the current of 26Wh at the voltage of 4.2V is 26wh/4.2v = 26wh/4.2v = 6.19ah = 6190mah, that is, at 100mA.

MA h is usually used as an indicator of battery charging and discharging, which is directly proportional to the charging (discharging) current and time of the battery. To make it comparable or convertible with Wh, it is necessary to know the battery voltage.

The second spelling of "hw-" can be traced back to 1 1 century, but it didn't become a common form until after15th century. It stands for "*kw-" of PIE, which is simplified as "w-" in German and "hv-", "kv-" or "v-" in Scandinavian.

It has not been etymologically added to some loanwords (why, why) and some local words (whole, whole) that once used simple "w-" or "h-".

It also threatened to change the spelling of "hot", "home" and many other words during its widespread use in the 0/5th century. It was sometimes changed to "quh-" (see Q) from16th century to18th century in northern England. In educated pronunciation, the correct pronunciation has always been controversial.

Wh- related vocabulary

The16th letter of the ancient Roman alphabet only appeared before words that started with vowels in English (,regardless of whether the word was pronounced (pique).

This letter comes from the Phoenician letters equivalent to the Hebrew letters koph and qoph, and is used in Semitic language to represent two deep and guttural "K" sounds. This letter existed in early Greek (there is no such difference) and is called koppa, but it is rarely used and is not included in the alphabet; Symbol (90) mainly used as numbers.