Unit 3 Flashcards
What are Kepler’s three laws?
The Law of Ellipses
Kepler’s first law - sometimes referred to as the law of ellipses - explains that planets are orbiting the sun in a path described as an ellipse.
The Law of Equal Areas
Kepler’s second law - sometimes referred to as the law of equal areas - describes the speed at which any given planet will move while orbiting the sun. The speed at which any planet moves through space is constantly changing. A planet moves fastest when it is closest to the sun and slowest when it is furthest from the sun. Yet, if an imaginary line were drawn from the center of the planet to the center of the sun, that line would sweep out the same area in equal periods of time.
The Law of Harmonies
Kepler’s third law - sometimes referred to as the law of harmonies - compares the orbital period and radius of orbit of a planet to those of other planets. The ratio of the squares of the periods to the cubes of their average distances from the sun is the same for every one of the planets.
Define what an electric field is?
a region around a charged particle or object within which a force would be exerted on other charged particles or objects.
Define what electric field strength is?
Electric field strength is a quantitative expression of the intensity of an electric field at a particular location. The standard unit is the volt per meter (v/m or v · m -1). A field strength of 1 v/m represents a potential difference of one volt between points separated by one meter.
What is electric potential energy?
Electric potential energy is the energy that is needed to move a charge against an electric field. You need more energy to move a charge further in the electric field, but also more energy to move it through a stronger electric field.
What is a magnetic field?
A magnetic field is the area around a magnet, magnetic object, or an electric charge in which magnetic force is exerted.”
Let’s put it this way. The invisible area around a magnetic object that can pull another magnetic object toward it or push another magnetic object away from it is called a magnetic field
True or False
A moving electric charge creates a magnetic field.
True
What is magnetic flux?
Magnetic flux is a measurement of the total magnetic field which passes through a given area. It is a useful tool for helping describe the effects of the magnetic force on something occupying a given area.
What is magnetic flux density?
The magnetic flux density or magnetic induction is the number of lines of force passing through a unit area of material, B. The unit of magnetic induction is the tesla (T).
What is electromagnetic induction?
Electromagnetic induction is where a voltage or current is produced in a conductor by a changing magnetic flux. It may happen when a magnet is moved in a solenoid, thus changing the magnetic flux.
What is Lenz’s law?
Lenz’s law allows us to predict direction of an e.m.f. induced by changing magnetic field through a loop or coil of wire (see Faraday’s Law). The e.m.f. will be directed so that if it were to cause a current to flow in a conductor in an external circuit, then that current would generate an extra magnetic field in a direction that would oppose the change in the original magnetic field.
What is Faraday’s Law?
It states that the induced voltage in a circuit is proportional to the rate of change over time of the magnetic flux through that circuit. In other words, the faster the magnetic field changes, the greater will be the voltage in the circuit. The direction of the change in the magnetic field determines the direction of the current.
Explain what Electromagnetic Induction is.
Induction (Electromagnetic Induction) - is the production of current in a conductor as it moves through a magnetic field. A magnet produces lines of magnetic force.
Due to Faraday’s Law of Induction if you take a wire and move it back and forth in a magnetic field, you cut across the lines of flux. The magnetic field pushes on electrons in the metal. This causes movement of electrons and is called electrical flow (current).
If you take a lot of wire such as in a coil and move it in the field, you create a more powerful “flow” of electrons.
How do transformers work?
Transformers consist of three main pieces: A core (typically ferromagnetic (iron)), and two individual sets of wire coils. The coils are referred to as the primary and secondary windings.
When applying AC current to the primary winding of the transformer, the coil creates a pulsing magnetic field. The core of the transformer works to direct the path of the magnetic field between the primary and secondary coils to prevent wasted energy. Once the magnetic field reaches the secondary coil, it forces the electrons within it to move, creating an electric current via electromotive force (EMF).
A transformer’s main function is to step-up or step-down the voltage from the primary to the secondary windings. This is done simply by adjusting the ratio of coils on one side to the other. If a transformer has 5 coils on the primary, and 10 on the secondary, it will be a 1:2 step-up transformer, meaning the voltage doubles from the primary to the secondary. Now on the flip side, if it has 10 coils on the primary, and 5 on the secondary, it would be a 2:1 step-down transformer, cutting the voltage in half.
