Final answer:
The energy of a body can indeed change only in small discrete units called quanta, which is a key concept of quantum mechanics and was a significant departure from prior classical physics.
Step-by-step explanation:
Energy Quantization and Quantum Mechanics
The statement that the energy of a body can change only in small discrete units, known as quanta, is true. This concept is one of the fundamental principles of quantum mechanics. Classical physics suggested that energy changes could occur in a continuous fashion, but observations such as the analysis of blackbody radiation led to the quantum theory. This theory shows us that energy is not exchanged in a continuous stream, but rather in discrete packets or quanta.
For example, electrons around an atomic nucleus occupy discrete energy levels, and an electron can only move to another energy level by absorbing or emitting a precise amount of energy - a quantum. These discrete shifts are far more modest than the term 'quantum leap' suggests. Planck's contribution to physics included the relationship between energy and frequency, described by the formula E = hv, where E is the energy of a photon, h is Planck's constant, and v is the frequency of electromagnetic radiation. This shows that energy is intrinsically quantized.
Moreover, on the macroscopic scale, some analogies illustrate quantization. Like only being able to take discrete steps on a stairway, or the impossibility of having a fraction of an atom, quantization is a principle that shows up in various physical entities, including energy.