They recorded the first references to electrical effects, such as static electricity and lightning, over 2,500 years ago. It was not until 1600 that a man named Dr. William Gilbert coined the term “electrica,” a Latin word which describes the static charge that develops when certain materials are rubbed against amber.
Answer:
The magnifying power of this telescope is (-60).
Explanation:
Given that,
The focal length of the objective lens of an astronomical telescope, 
The focal length of the eyepiece lens of an astronomical telescope, 
To find,
The magnifying power of this telescope.
Solution,
The ratio of focal length of the objective lens to the focal length of the eyepiece lens is called magnifying of the lens. It is given by :


m = -60
So, the magnifying power of this telescope is 60. Therefore, this is the required solution.
Mechanical because it's physically vibrating and is caused by a physical action.