Answer:
when the direction of the Current changes.
Explanation:
Electromagnet refers to an iron ore wrapped around with a coil of wire, in presence of electric current. As it acts like a magnet, when current is passed through it.
The north & south poles of magnetic fields produced by such magnet, change with direction of current passed through it.
Answer:
Difference threshold or also Just Noticeable Difference
Explanation:
The above mentioned case between room mates, where one room mate was able to detect a minute change in volume shows an instance of the difference threshold.
Difference threshold can be defined as stimulation at its minimum level that can be detected by an individual almost 50 % of the times.
It is the lowest possible level of sound that is detectable by a person.
That is what happened in the mentioned case that when the volume was increased from 14 to 15, Amber was able to detect it.
