Physics Flashcards
What is a field?
a 3-D area that feels the effects of force
What properties do fields have?
All fields have a source, direction, and magnitude.
How many types of fields are there and what are they?
There are three types of fields: Electrical field, gravitational field, and magnetic fields.
True or False: You can observe a field indirectly
False
How do you determine the direction of the fields?
Test Objects
What kinds of test objects are there for gravitational fields?
Anything light (books) Any rock in space (moons)
What kinds of test objects are there for Electrical fields?
Hair
Ink
What kinds of test objects are there for magnetic fields?
Iron filings
Ions from the Sun
What is Gravitational Field Strength?
The amount of Newtons/kilogram a test body (a small mass) will experience at a certain distance from the source of the gravitational field.
What are field lines?
Non-intersecting lines, drawn in mapping a Vector
What is Gravitational Fields?
Space surrounding a mass. Gravity keeps objects on the earth (Gravity is actually infinite, but gets weak very quickly).
What characteristics are there in Gravitational Fields?
Source: any object with mass
Direction: always towards the center of the object (only pulls)
Strength measured in N/kg
What is Electrical Fields?
an electrical field is a region surrounding a changed object. Electrical fields are used in copiers and other electrical technologies.
How do objects become charged?
Recall atoms made of a “+” nucleus and “-” electrons orbiting the nucleus
Charges are neither created nor destroyed, just transferred
When one objects rub against another, electrons are transferred from one material to another
Conductors are materials that allow electrons to move freely (ex. Copper and aluminum)
Insulators do not allow electrons to move freely, but can have their charges build up (ex. Cloth, fabric)
What is Electrostatic Attraction?
Opposite charges attract and same (like) charges repel. The more charged an object is, the greater the force is repulsion or attraction.
What are Electrical Field Characteristics?
Source: any object with a charge
Direction: towards the negative charge
Both attract and repel
Strength: measured in N/C
What is Grounding?
Allows electrons to flow into the Earth
What are Lightning Rods?
Lightning Rods are connected to the ground to help direct electrons below the surface of the Earth.
True or False: A lightning bolt will always take the shorted path and will likely strike a tall conductor first
True
What is a Current?
Symbol is I and the units is Amps (Ampere’s) (A)
How many electrons (how much charge) passes a point in 1 second
What is Electrical Energy?
Energy due to a moving charge (voltage) (V)
What is Mechanical Energy?
Energy a moving object contains or due to its poisition
What is Chemical Potential Energy?
Energy contained in bonds of a chemical substance
How many and what kind of Circuit(s) are there?
2
Series and Parallele circuits
What is a series?
A circuit where there is a simple single loop. When one burns out they all die
What is a parallel circuit?
A circuit where there are loops within a loop. There are multiple pathways for currents to flow. When one burns out, the others keep working
What happens when a battery is connected to a series circuit?
Voltage adds up
What happens when a battery is connected to a parallel circuit/
Voltage is on average
What is a resistor?
A resistor is any device in a circuit that disrupts electron flow, generating heat (thermal heat) or light
What is resistors measured in?
Ohms
What are currents measured in?
Amps
What are energy sources measured in?
Volts
What are two forms of radiation that comes from the sun?
Solar wind particles and electromagnetic radiation (EMR)
What properties does EMR (electromagnetic radiation) have?
Changing electric and magnetic fields
The sun is the source of all energy except for what?
Geothermal energy
How is an EMR made?
A moving charged particle
What is sound?
A wave that is transmitted through particles in the air
Why is EMR a transverse wave?
because the direction of the vibrations are at right angles to the motion of the wave
What are the many sources of EMR?
Radiowaves, TV, Microwaves, and Shortwaves: electronic circuits
Infrared Wave (IR): vibration of atoms in all warm and hot substances
Visible Light: Electrons jumping through energy levels in very hot objects (ex. The sun, candles, white hot filament of incandescent light bulb, etc.).
Ultraviolet Light (UV Light): Dangerous rays from the sun, special “black light” bulbs
X-Rays: special cathode ray tubes where electrons collide with metal plates
Gamma Rays: Radioactive sources where electrons are ejected from the nucleus by very powerful nuclear forces
What are the many wave properties of EMR?
Reflection: bounces off polished metal surfaces (ex. Silver coating of mirrors).
Refraction: bends towards the normal when entering optically dense materials such as water and glass
Diffraction: bends around objects and spreads when going through openings provided the object or opening is about the same size as the wavelength of the EMR
Interference: Interference patterns (light and ddark regions) form when EMR pass through double slits or multiple slit openings
Polarization: EMR shows a flat transverse nature that can be detected using polarizing lens
Wavelength: The distance required for one complete cycle of a wave
Frequency: How often a wave cycle passes a point, how frequently the waves are coming.
True or False: Radio waves are Longest in wavelength, lowest in frequency, and low in energy
True
True or False: Radio waves do not require antennae
False
What is AM
AM is amplitude modulated wave
What is FM
FM is frequency modulated wave
True or False: High Voltage power lines can create EMR waves at low frequencies
True
What is an MRI
allows non-invasive examination of body tissues, not good to see bones or certain tumors
MRI - aligns specific nuclei of certain isotopes in our bodies (recall an isotope is an atom with different number of neutrons than normal) by using a VERY strong magnetic field. Causes nuclei to align with the field, but requires energy to do this. Radio waves are used as a source of energy for the nuclei, and the interaction can be viewed by computer and used to create an internal photo of the body.
True or False: Light is generated in all directions, but radio waves are polarized - generated uniformly in one direction and plane
True
What does LASER stand for?
Light Amplification by Stimulated Emission of Radiation
What kind of animals can sense infrared?
Mosquitos
True or False: Humans can not sense infrared
False. Humans sense infrared through heat
True or False: Humans can not give off infrared
False. Humans give off infrared through cellular respiration
What are constellations
a group of stars that appears to form a pattern or picture
What is astronomy?
The study of everything beyond the Earth’s atmosphere
What is Nuclear fusion?
the process that powers active or main sequence stars and other high-magnitude stars, where large amounts of energy are released.
What is the nearest star from Earth?
The sun
What is Reflection?
abrupt change in the direction of propagation of a wave that strikes the boundary between different mediums.
What is Refraction
the change in direction of a wave passing from one medium to another caused by its change in speed
What is Polarization?
a phenomenon caused due to the wave nature of electromagnetic radiation.
What is Diffraction Patterns?
The interference pattern that results when a wave or a series of waves undergoes diffraction, as when passed through a diffraction grating or the lattices of a crystal.
What is Resolution
the spreading of waves around obstacles
What is False-Color Image?
color in an image (such as a photograph) of an object that does not actually appear in the object but is used to enhance, contrast, or distinguish details.
How are radio waves emitted by the sun?
Solar flares
What is Solar Flares?
an intense burst of radiation coming from the release of magnetic energy associated with sunspots.
What is TIR?
Total Internal Reflection
What are the two requirements for TIR?
- the light is in the more dense medium and approaching the less dense medium.
- the angle of incidence is greater than the so-called critical angle.
What is Diffraction Grating?
an optical component with a periodic structure that diffracts light into several beams travelling in different directions
What is Continuous Spectrum
an emission spectrum that consists of a continuum of wavelengths.
What is Absorption or Dark-Line Spectrum
An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies
What is Emission or Bright-Line Spectrum
an emission spectrum consisting of bright lines against a dark background
What is Spectra
the intensity of light as it varies with wavelength or frequency
What is Spectrometer
an apparatus used for recording and measuring spectra, especially as a method of analysis
What is Absorption and Emission Spectrum
The emission spectrum is the spectrum of radiation emitted by a substance that has absorbed energy
What is the Doppler Effect?
When an object is making noise and is moving away or towards you
What is the Doppler Effect?
When an object is making noise and is moving away or towards you
What is the Red Shift?
the displacement of spectral lines toward longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects. This is interpreted as a Doppler shift that is proportional to the velocity of recession and thus to distance.
What is the Blue Shift?
the displacement of the spectrum to shorter wavelengths in the light coming from distant celestial objects moving toward the observer.
What is the Red Giant?
a very large star of high luminosity and low surface temperature. Red giants are thought to be in a late stage of evolution when no hydrogen remains in the core to fuel nuclear fusion.
What is a Nebula?
a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.
What is the White Dwarf?
a small very dense star that is typically the size of a planet. A white dwarf is formed when a low-mass star has exhausted all its central nuclear fuel and lost its outer layers as a planetary nebula.
What is a Supernova?
a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
What is a Star?
a fixed luminous point in the night sky which is a large, remote incandescent body like the sun.
What is a Neutron?
a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
What is a Black Hole?
a region of space having a gravitational field so intense that no matter or radiation can escape.
How is a black hole formed?
when the center of a very massive star collapses in upon itself.
