Isaac Newton's Law of Universal Gravitation was used to predict the position of planets based on their mutual force of gravity. From about 1820 it was noticed that the predicted position of was different than the actual position. Some astronomers correctly thought that an unknown planet was the cause of the difference, allowing for the discovery of .

From about 1820 it was noticed that the predicted position of Uranus was different than the actual position. Some astronomers correctly thought that an unknown planet was the cause of the difference, allowing for the discovery of Neptune.

Explanation:

Uranus was discovered by William Herschel in 1781. In the early 19th century odd perturbations in the orbit of Uranus led to astronomers to speculate with the existence of an unknown planet located farther away whose gravitational tug affected Uranus orbit. The observations made of the position  of Uranus did not agree with those predicted by Newton's Law of Gravitation.

In September of 1846 the astronomer Urbain Le Verrier made calculations based on the data available and predicted the position of this hypothetical planet. Then on September 23 of that year Neptune was observed for the first time by Johann Galle at the Berlin observatory.

c.the charges if the proton and electron and gravity

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia