The phrase "an example of this principle" is correct and usable in written English.
You can use it when you want to illustrate or clarify a principle by providing a specific instance or case that demonstrates it.
Example: "To better understand the concept of gravity, let me provide an example of this principle: when an apple falls from a tree, it is being pulled towards the Earth by gravitational force."
Alternatives: "a case in point" or "a demonstration of this principle".
The military security rule of "need-to-know" is an example of this principle.
As an example of this principle, an effective altruist would consider disaster relief funding as an unwise investment because this cause already receives a large influx of donations.
As an example of this principle in action, Norton points to a non-profit called DonorsChoose.org, which allows "anyone to find a specific classroom in a specific town with a specific need and donate directly to that classroom". Making it specific and personal can help education leaders expand the in-group to include many groups of people, by building a sense of outsiders' humanity.
Here's an example of this principle involving my daughter, Chelsea, a high-school lacrosse player.
The US Supreme Court case Hirabayashi v. United States (1943) is an example of this principle.
In a recent issue of Breast Cancer Research, Keller and colleagues [ 1] report an example of this principle: sustained propagation of large numbers of cells, through the establishment of cell lines, disrupts the normal balance between differentiated cells and their progenitors, as observed in fresh biological specimens.
This was an example of the principle of restricted choice: when an honor falls, it is likely to be because the defender has no choice in the matter.
This may be an example of the principle that an accumulation of risk factors is especially harmful [ 25, 55].
It was an example of the principle of negative modeling.
"It's an example of the principle of 'there's no free lunch,' " Mr. Cassidy said.
Pythagoras believed that the mathematical order to music was an example of the principle of number which underlies the universe.
