The changes on a microscopic level is that the particles move faster and thus move to higher energy levels.
When we talk about the microscopic properties, we are talking about the properties that concern the small particles in the substances. We know that the solid is composed of atoms and the atoms have electrons. This is the basis of the movement of particles.
When the surface of the metal is continuously struck, a greater magnitude of energy is supplied to the particles that are contained in the metals and they tend to move from a lower to a higher energy level due to this excitation.
Part of the energy that is taken in as the particles are excited are given out as they return to the ground state and this responsible for the light that can be seen as the metal is further struck with the harmer.
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