The object that attracts iron and other materials that have magnetic qualities similar to iron is a what? ​

Which process does not require the presence of a physical substance in order to transfer heat? air in the atmosphere is heated by the ground. this warm air then rises, and cooler air falls. this is an example of what type of process? how is conduction different from radiation?

How have the greenhouse gasses increased from the year 2000 to 2018

When a device is used in a circuit in which the voltage is 81 v the current flowing through the device is 3 a what is the resistance of the device