What is the main reason that the earth's interior is liquid today? tidal force of the moon on the earth seismic waves that travel through earth's interior decay of radioactive elements convective motions in the mantle?

Because of the earth surface and the interior of the earth decay into radioactive elements convective motion in the mantle

The main reason that the earth's interior is liquid today is decay of radioactive elements.

About 50% of the internal heat of the earth produced from radioactive decay. Four radioactive isotopes are mainly responsible for the most of the radiogenic heat.

These radioactive isotopes are uranium-238 (238U), uranium-235 (235U), thorium-232 (232Th), and potassium-40 (40K).

Therefore, the main reason that the earth's interior is liquid today is decay of radioactive elements.

To know more about seismic waves,

the current is 0.6

voltage ÷ resistance = current

so 12 ÷ 20 = 0.6

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