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Robert MillikanOil drop experiment
Used to determine the charge on an electron.
Static force is equal to gravitational force so drop is suspended.
Eq = mg
q = mg E
Frederick Soddy
Used the idea of charge to mass ratio show that isotopes exist.
Isotopes are atoms of an element with the same chemical properties but different atomic mass.
Mass Spectrometer-to determine the concentration of isotopes in an element
Charged particles are deflected differently due to their mass.
Cathode Ray Tubes- Deflect electron beams through a magnetic coil or charged plates. This hits the back of a screen covered with phosphors that give off light.
Wilhelm Röntgen
X-ray- High energy, high frequency wave emitted by some cathode ray tubes.
Original x-rays were difficult to control and often caused severe skin burns. He varied the electric potential to control the x-ray and reduce burns.
Lead screen is used to reduce cell damage.
Radio- Uses electromagnetic waves to transmit and receive signals
AM radio- amplitude variations
535-1705 kHz
FM radio-frequency variations.
88-108 MHz
Cell PhonesCell Phones
Operate at 825-900 MHz. High frequency means there is a stronger signal and a shorter antenna can be used.
Radio SignalsRadio Signals
Other uses: toys, garage door openers, baby monitors, satellites, police radio, GPS, weather
EMF= V =BLv
V- potential difference(V) L- length of wire(m) B- Magnetic Field (Tesla) v- velocity(m/s)
Ex: An antenna on a remote control car is 0.20m long and is traveling at 7.0m/s through a magnetic field of 8x10-2 Tesla. What EMF is induced in the antenna? V= BLv V= 8x10-2T(0.20m)(7.0m/s) V= 0.112V
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