The first one would be thermal energy
Explanation:
The compass needle moved when the wire was connected to the battery. The important point here is that the needle is affected by the wire only when both ends of the wire are connected to the battery because only at this time is current flowing through the circuit.
Explanation:
Let f is the frequency of an oscillation and T is the period of the oscillation. There exists an inverse relationship between the frequency and the time period of the oscillation. Mathematically, it is given by :

Also, 
So,

The time taken to complete one oscillation is called the period of the oscillation and the number of oscillation is called the frequency if an oscillation.