Is this Conduction, Convection, or Radiation:
The top floor of a building is the warmest.

convection

Explanation:

hot air rising is a common example of heat convection

Radiation

Explanation:

Radiation is like for example the sun gives out the radiation from it's heat and for the example you have the heat from the stove is warming the house up from it's radiation waves.

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete

no. dot product   =0 when vecs at right angles