1876 On February 4th, Bell applied for a telephone patent in the US Patent Office. 10 In March, Bell obtained a patent for telephone invention, announcing the arrival of a new era of mankind. 1878, Bell established the telephone company, and realized the long-distance telephone test between Boston and new york, which are 300 kilometers apart. Since then, the telephone has spread rapidly in major cities in North America, and quickly swept the world. 1900, the first local telephone in China also appeared in Nanjing.
Bell has made outstanding contributions in the fields of acoustics and electricity;
He obtained more than 30 patents, half of which were published by telephone. His name "Zhong" was later used as a unit to measure sound intensity level in acoustics, and also used to calculate the ratio of current to voltage and the ratio of output to input power in electricity.
However, Bell was not the only one who invented the telephone. A man named Gray once filed a lawsuit with Bell over the telephone patent right. They filed the patent on the same day, but Graybeal Bell was about two hours late and finally lost the case.