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89 Cards in this Set
- Front
- Back
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What particles are in the atom? What electric charges do they have? |
Electrons that are negatively charged Protons that are positively charged Neutrons that are uncharged. Nucleus contains protons and neutrons |
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Difference between gravitational and electrical forces? |
Gravitational forces always attract Electric can attract or be repulsive. |
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Who discovered the law of force between electric charges? |
Coulomb |
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Difference between conductors and nonconductors? |
Conductors have free electrons that roam-Non conductors do not have free electrons |
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What charge transfer occurs when (a) plastic is rubbed with fur (b)glass is rubbed with silk |
(a) electrons transfer from fur to plastic giving it negative charge. (b) electrons transfer from glass to silk leaving glass with pos charge |
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How can a stream of water or wooden board move by a charged rod? |
Water molecules have pos and neg sides(dipole) pos molecules move towards neg rod. |
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Instrument used to detect presence of electric charge |
electroscope |
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What causes the sparking when a grounded rod is near a van de graff? |
When molecules and atoms get excited they emit light |
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What is an electric current |
Flow of Electric charges |
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Charge quantization Phenomenon |
No charge smaller than e= +or- 1.60217657 x 10^-19 x C |
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Electromagnetic Shielding |
Car protecting you from lightening |
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Under what conditions is water a conductor of electricity? |
Pure water not a conductor - could contain salt or acid |
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Under what conditions is gas a conductor of electricty |
Neutral gas not a conductor, some gas molecules can be ionized from large voltage>plasma |
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Basic constituents of a battery |
2 Different metals and some substance(acid) to allow a current to flow |
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Effect battery produces in an electric circuit |
Battery produces electric field that pushes electrons that carry current |
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What gives rise to electrical resistance in a conductor? |
Electrons collide with ions with slows them down moving in zig-zag |
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What is relation between current, voltage, and resistance? |
Ohm's Law> V=IR |
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What is electrical power consumes in a circuit, how is it calculated? |
electrons move through conductor and collide with ions to produce heat > P=IV=i^2 x R |
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Why are power strips limited by a current rating? |
Max electrical current the power strip can handle safely |
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Difference of series and parallel connections |
Devices in series have same current passing though
Devices in parallel have same voltage |
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What is DC (Direct Current) |
Current always flows in one direction Produced by batteries |
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What is alternating of AC electrical power? |
Current reverses direction 60 times per second |
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How is AC power produced> |
In an electrical generator which consists of a coil wire that is rotated in a magnetic field. |
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Advantages of AC vs DC power |
Voltage in AC power can be changed using transformers AC plants can be located far from cities |
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Energy sources used to produce AC power(4) |
Steam produced in fossil fuel burning/nuclear power plant Hydroelectric power Wind power |
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What is the role of transformer in electric power grid? |
Used to step-up voltages coming from power plant for transmission - then stepped-down for distribution to homes |
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What is a Ground Fault Circuit Interrupter(GFCI) |
Electrical safety device that detects small amounts of current flowing in ground circuit - prevent electric shocks |
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Why is AC transmitted at high voltages? |
Power is more efficiently transmitted at high voltage and low currents |
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Electricity bill payed for power used or energy? |
Cost for the total amount of energy used over certain period. |
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Why is it better to replace incandescent lights with fluorescent? |
Fluorescent lights produce less eat and more efficient and produce same light output with less power. |
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What are the 2 types of magnets? |
Permanent and electromagnet |
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What is general direction and shape of magnetic fields? |
Always have north and south pole Field points from north to south Field lines always form closed loops |
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(a)What is the shape of the earth's magnetic field (b)Why does a compass point north? |
(a) points in direction from south geographic pole to north geographic pole (b)Geographic north pole of earth is the south magnetic pole |
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What are the Van Allen Radiation belts? |
Two regions surrounding earth that have large accumulation of charged particles trapped in magnetic field. |
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What is the effect of a magnetic field on a charged particle? |
Magnetic field produces a deflection on moving charged particle Charged particles revolve around magnetic field lines in spiral orbits |
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What is electromagnetic induction? Who Discovered it? |
Current induced in a coil if the magnetic field that penetrates through the coil changes in any manner |
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Why do transformers not work with DC? |
Only work if the current in the primary changes in time. |
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What is Maxwell's contribution to the laws of electricity and magnetism? Hertz? |
Theorized that a changing electric field would generate a magnetic field Hertz demonstrated
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What is an electromagnetic wave? |
combination of time-varying electric and magnetic fields that propagate through space at the speed of light |
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What is the index of refraction? |
the ratio of the speed of light in vacuum to speed of light in a medium. |
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What is phenomenon of refraction |
bending of light ray as it enters boundary between two materials |
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How a ray bends: (a) Ray from air to glass? (b) Ray from water to air? |
(a) Bends towards normal (b) Bends away from normal |
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What is dispersion? |
Name for the fact that the index of refraction of a material depends on the wave length of light -also causes formation of rainbows |
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What phenomenon is the cause of blue skies and red sunsets? |
Result of scattering of sunlight from air molecules |
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What is the law of reflection? |
The angle of reflection = the angle of incidence |
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How are parallel rays reflected by a concave mirror? |
Reflects rays to a single focus point |
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How are parallel rays reflected by a convex mirror? |
Diverge rays from a focal point |
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Real Image |
Light rays converge at image location |
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Virtual image |
Rays diverge when they leave the object and appear to come from a point where no light rays actually are |
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What principle of optics explains how lenses work? |
Refraction |
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What type of image is formed of an object located far from a converging lense |
Image is real and inverted |
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Corrective lens for nearsightedness? |
Diverging Lens |
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Corrective lens for farsightedness? |
Converging |
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Plane mirrors only produce ______ images |
Virtual. |
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Diffraction |
Spreading out of light waves after passing though small opening |
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Polarized Light |
Light wave where electric field always vibrates along one direction |
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Unpolarized light |
Electric field oriented randomly in all directions |
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Constructive interference |
Reinforcement (combine) |
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Destructive interference |
Cancellation |
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How diffraction effects distinguishing closely spaced objects |
causes light entering out eyes to spread 2 objects overlap, appear as one (Headlights) |
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Thin film - DVD |
White light spread out by/in color) |
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Photoelectric effect |
when metal surface exposed to light, electrons are emitted from metal |
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Einstein use the _______ concept to explain photoelectric effect. |
Photon |
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What is a Photon |
quantized packet of energy |
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Who used photon concept to explain stability of hydrogen atom |
Bohr |
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What is the stationary state of an atom |
Special quantum state of electron in which it does not radiate |
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Difference between emission and absorption |
Emission- electron jumps from high energy to low Absorption- electron in low energy can absorb a photon and move to high energy |
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What is fluorescence |
A substance absorbs a high energy photon and immediately emits lower energy photon |
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What is the Heisenberg uncertainty principle? |
State it is impossible to determine position and velocity of an electron simultaneously with unlimited accuracy. |
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x-Ray |
does not penetrate through dense(bone) tissue |
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Tomography |
computer process that images taken from many different angles. CAT scan |
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Types of electromagnetic radiations used in CAT and MRI |
CAT scan uses x-rays MRI uses harmless radio waves |
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What holds the nucleus together |
Nuclear force |
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Z is number of ____ N is number of____ __ = __ + __ |
Z-Protons N-Neutrons A = Z + N
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What are isotopes |
Nuclei of the same element (same Z) |
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Ampere |
How currents produce magnetic fields |
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Bohr |
Theory of hydrogen atom > stationary state |
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Coulomb |
Force law between two charges |
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Curie |
Discovered Radio Activity 1st women nobel prize winner
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Einstein |
Phtotoelectric effect mass emercy |
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Faraday |
Electromagnetic Conduction |
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Fermi |
Father of Atomic bomb |
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Galileo |
1st to attempt measure of speed of light |
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Heissenboro |
Uncertainty Principle |
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Hertz |
Discovered Electromagnetic waves lab |
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Maxwell |
Predicted existance of Electromagnetic waves |
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Meitner |
Discovered Fission |
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Oersted |
Currents deflect compass |
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Teller |
H Bomb |
