phys
4. 1. Electromagnetic wave (light) does not require a medium, mechanical (sound) does. 2. Longitudinal Wave- Particles oscillate parallel to wave. Transverse- Particles oscillate perpendicular to wave. Surface- Particles oscillate in a circle relative to waves motion. 3. More particles=faster sound travel. Less dense medium equals slower sound travel. No particles equals no travel of sound. 4. Outer ear acts like a funnel to allow sound waves to enter. They strike your ear drum which vibrates three small bones in the ear, then striking the cochlea. Small hairs of different lengths move, sending signals to your brain which interprets them a sound 5. Hotter air=faster sound travel. Colder air=slower sound travel. 6. As frequency increases wavelength decreases. They have an inverse relationship. 7. Sounds loudness is decibels dB, threshold of hearing 20-30 dB, pain= 120-130 dB. 8. Pitch’s units are hertz Hz. Human range 20-20,000 Hz. 9. Ultrasound occurs above 20,000 Hz. (Dolphins and echolocation) Infrasound occurs below 20 Hz. (elephants use them to communicate) 10. Frequencies how many waves per second. The period is how many seconds per wave. inversely proportional
11. The Doppler effect is the perceived change in pitch due to the motion of sound. There’s a sound source moves, the sound waves produced pile up in front of the sound, causing a shorter wavelength and higher frequency. 12. Nodes are the location of no vibration or motion destructively interfering. Antinodes are the location of Max vibration. Constructively interfering. 13. Resonance is the increased loudness when two waves constructively interfere usually in instruments. 14. Acoustic levitation Matching ultrasounds are played from two speakers facing each other to produce a standing wave, at the nodes a small object can be placed because the waves are destructively interfering, no vibration. 15. At certain frequencies the plates vibrate in the way so there are locations with nodes and antinodes. Sand sprinkled on the plate will settle in the nodes. 16. Open pipes will produce standing waves with anti-nodes at both ends. Length doubled = wavelength of fundamental frequency. Closed pipes will produce standing waves with an anti-note at one end and a note at the other. Length x4 = fund. Freq. 17. 18. 19. 20. 21.
5. 1. Iron, nickel, cobalt can be used to produce permanent magnets. Magnetite is naturally occurring magnet. 2. Magnetic domains are very small portions of a material. Each domain acts like a tiny magnet because of the electrons. Domains lineup=magnetic. 3. Distance, temperature hot=weak, condition, material, size and shape all effect on magnets strength. 4. Compasses contain a very small magnet that is placed so that friction is greatly reduced allowing the magnet to spend. Aligns with magnetic north. 5. Repelling magnets have higher energy when close together. 6. Gauss gun- ball is flicked, movement near magnet causes ball to be attracted and speed up. Once it strikes the magnet, the energy is transferred through the magnet into the next ball. 7. Humans blood is diamagnetic, and has little iron. 8. Friction: two neutral objects rubbed together, electrons move from one to the other. Both become charged. Conduction: charged object touched to neutral object, electrons move from one to the other. Induction: charged object held near neutral. Electrons cannot move, particles inside object realign, temporary charged object. 9. Electric force has inverse relationship with distance. Mag force and grav. force have inverse relationship with distance 10. attracting charges have low energy one close together. 11. Magnetism and electricity. Same because: they have forces fields polls and a related to strength of charge, distance, opposites attract like repels. Different because: can only have one charge/can I have one pole , can see magnets easier than charges. 12. Connect battery to magnet, to make stronger make wire into coil, insert iron/magnetic material into core of coil, thinner wire or larger battery. 13. Electromagnetic induction is the generation of a current in a wire because of a changing magnetic field that it’s self was created from a changing current. 14. Generators take mechanical motion and generates electricity. Motors take the electricity and generates mechanical motion. Set up can be identical, input/output are the only thing that changed. 15. Difference between electromagnets and electric motors: Motor requires second magnet to interfere with magnetic field. Without second magnet, they are identical. 6. 1. Light has dual nature. It’s a wave and particle. Photoelectric =particles. Double slit=waves. Light can’t be explained without duality. 2. Photoelectric- Light shines in metal plate. Blue light causes electrons to fly off. Photons of blue have enough energy to collide with electrons. 3. Double slit- light goes through 2 small close slits. And interference pattern appears on the screen. Light=wave. 4. Gamma treats cancer, X-rays medical imaging, ultraviolet sterilization, visible seeing, infrared thermal imaging, microwaves cooking, radio waves communication. 5. Spectrum has very large and small numbers. Linear scale would have to stretch across cities. Logarithmic can be easily condensed to see scale. 6. Light = movements of photons elec. field made by charged particle creates wave as particle moves, creating perpendicular mag field. 7. Speed of light c=3×10^8 m/s -Universal Speed Limit (nothing travels faster than that) 8. Energy and freq are proportionally or directly related. If one increases the other does as well. 9. Low Energy- radio and micro High Energy- X-rays and gamma (high ultra) 10. Ionizing Radiation- There is enough energy that the EMR can rip electrons from atoms, creating ions. 11. Light interference- Reflection- light bounces back when it hits a boundary. Diffraction- lights bends around boundary. Polarization- diffraction with many slits. Refraction- light changes speed when it encounters new mediums, may bend due to change in speed. (Mirages) Dispersion- refraction but with white light. Wavelength = dependent, diff colors bend differently and separate in medium. 12. Mirages- light travels at diff speeds at diff temps. Faster through cold air Near the surface, differing temps creates barrier for light. Light refracts and bends. Eyes don’t see the bend and interprets it as straight movement. 13. Light travels slowest through solids, dense particles slow down light. 14. Luminous- source of light Luminous- reflect light 15. Transparent- transmit light, light and detail of object. Translucent- semi-transparent, see light, no detail. Opaque- shield light, light does not go through. Tesla Coil- Circuit to battery, switch turns circuit on and off quickly creates changing mag field.