The phrase "full amplitude" means the highest point or intensity reached by something. It refers to the maximum level or magnitude of a certain phenomenon or measure. Full definition
The full amplitude of the just war tradition would be capable of considering such components of complicity and even entrapment as part of the definition of just cause, but our public discourse has consistently described the case as if the history of Mesopotamia began in August. (religion-online.org)
We continue to read Russian literature because it shows the full amplitude of the soul, from the bestial to the holy. (firstthings.com)
The full amplitude of solar cycle forcing is about 0.25 W / m2 [64], [71], but the reduction of solar forcing due to the present weak solar cycle is about half that magnitude as we illustrate below, so the energy imbalance measured during solar minimum (0.58 W / m2) suggests an average imbalance over the solar cycle of about 0.7 W / m2. (journals.plos.org)