That's a very difficult question to answer, because you give us
no information regarding what you have done in your life.
We can only assume that you have most likely breathed on occasion,
floated on your back in the ocean, lake or pool, maybe fallen off of a
ladder or out of bed, felt the warmth of the sun on your cheek, seen
a rainbow after a rainshower, heard the sound of thunder during a
summer storm, taken a trip in an airplane, and waited for a cup of
hot chocolate to cool off. The richness of any of these experiences
is greatly enhanced when you understand some of the Physics involved.
Explanation :
It is given that,
Diameter of the coil, d = 20 cm = 0.2 m
Radius of the coil, r = 0.1 m
Number of turns, N = 3000
Induced EMF, 
Magnitude of Earth's field, 
We need to find the angular frequency with which it is rotated. The induced emf due to rotation is given by :




So, the angular frequency with which the loop is rotated is 159.15 rad/s. Hence, this is the required solution.
Answer:
False
Explanation:
False, as a magnetic field is generated whenever current travels through a conductor.
An electromagnet consists of a coil of wire wrapped around a bar of iron. The coil and iron bar get magnetized when electric current flows through the wire. An electromagnet also has north and south magnetic poles. The magnetic field is strongest at either pole of the magnet.
U=1/2kx2
This image sums it up
I do believe the answer is land because the ocean/sea gets cold when its night. So the answer is land