An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?
Answer (2)
When a current of 15.0 A flows for 30 seconds, the total charge transferred is 450 coulombs. Dividing this charge by the charge of a single electron (1.6 x 10^-19 C) gives approximately 2.81 x 10^21 electrons. Hence, about 2.81 x 10^21 electrons flow through the device.
;
To effectively explain how a Foucault pendulum provides evidence of Earth's rotation, we must first understand what a Foucault pendulum is and how it operates.
A Foucault pendulum is a simple device consisting of a large, heavy ball attached to a long cable, which allows it to swing freely back and forth. This pendulum was first devised by the French physicist Léon Foucault in 1851 to demonstrate the rotation of the Earth.
Here's a step-by-step explanation of how it works:
Swinging Path : When the pendulum is set in motion, it swings along a fixed plane in space, determined at the point of release. This path is initially straight, and in the absence of external forces, would continue in the same direction.
Earth's Rotation : However, because the Earth rotates on its axis, the ground beneath the pendulum moves. To an observer standing on Earth, this makes it appear as though the pendulum's swing path is gradually rotating over time.
Evidence of Earth's Rotation : This apparent shift in the direction of the pendulum's swing provides tangible evidence of Earth's rotation. The rate of this apparent rotation depends on the latitude of the pendulum's location. At the North or South Pole, the swing would make a full rotation in 24 hours, while at the equator, it wouldn't rotate at all.
Observation : By observing a Foucault pendulum in a museum or other public spaces like the Nicolaus Copernicus Museum in Frombork, Poland, people can visually and practically understand that Earth is rotating beneath us, even though we don't feel it.
Based on this understanding, the choice that most effectively uses the relevant information to explain how a Foucault pendulum demonstrates Earth's rotation is:
B. Though it swings on an unchanging path, a Foucault pendulum appears to change its swing path over time because Earth rotates beneath it.
This choice clearly conveys the reason for the apparent change in the swinging path and directly links it to the rotation of the Earth, fulfilling the goal of explaining how a Foucault pendulum provides evidence of Earth's rotation.
