Mostly Light
By observing eclipses of Jupiter’s moon Io, this scientist found that light took longer to arrive when Earth was farther from Jupiter.
Who was Ole Rømer?
Alternating bright and dark fringes appeared when light passed through two narrow openings in this famous experiment.
What is Young’s double-slit experiment?
This phenomenon occurs when electromagnetic radiation causes electrons to be emitted from a metal surface.
What is the photoelectric effect?
Deflection of cathode rays by electric and magnetic fields showed that the rays consisted of negatively charged particles.
What was Thomson’s cathode-ray experiment?
The gold-foil results showed that almost all the atom’s positive charge and mass were concentrated in this region.
What is the nucleus?
This scientist conducted the first terrestrial experiment to determine the speed of light.
Who was Fizeau?
Formula for bright fringes occur when the path difference is an integer multiple of the wavelength.
What is mλ?
Increasing this property of light increases the photoelectric current but not the maximum kinetic energy of the emitted electrons.
What is intensity?
Thomson used electric and magnetic fields to determine this property of the electron.
What is the electron’s charge-to-mass ratio?
The discrete lines in hydrogen’s emission spectrum provided evidence that electrons can possess only these values. (Name and scientist)
What are Bohrs quantised energy levels?
In an experiment involving light, the returning light disappeared when this part of the rotating apparatus blocked it.
Toothed cogwheel (Fizeau)
This equation calculates wavelength using fringe separation x, screen distance L and slit separation d.
What is wavelength = xL/d?
Below this value, no photoelectrons are emitted, regardless of the light’s intensity.
What is the threshold frequency?
Charged oil drops were suspended by balancing their weight with an upward electric force in this experiment.
What was Millikan’s oil-drop experiment?
This scientist proposed that electrons can act as standing wavs in their atomic orbits and suggested that if light has both wave and particle traits, matter like electrons also has both.
Who was De Broglie?
When uranium was bombarded with neutrons, barium was unexpectedly produced. Meitner and Frisch interpreted this as this nuclear process.
What is nuclear Fission?
Only waves that oscillate perpendicular to their direction of travel can display this effect, proving that light is transverse.
What is polarisation?
Einstein used this equation to explain the photoelectric effect.
What is hf = work function + maximum kinetic energy?
Millikan found that the charges on different oil drops were always whole-number multiples of this value.
What is the elementary charge, 1.60 × 10⁻¹⁹ C?
Chadwick bombarded this element with alpha particles to produce highly penetrating neutral radiation.
What is beryllium?
This experiments null result provided evidence against the luminiferous aether and supported the idea that the measured speed of light does not depend on Earth’s motion.
The Michelson-Morley experiment
Radio waves produced by a spark-gap transmitter were reflected, refracted, interfered and polarised in this scientist’s experiment.
Who was Heinrich Hertz?
Millikan plotted stopping voltage against frequency. The gradient of this graph was equal to this quantity.
What is Planck’s constant divided by the elementary charge, h/e?
Most alpha particles passed through gold foil, but a very small number were deflected through large angles or backwards.
What was the Rutherford or Geiger–Marsden gold-foil experiment?
Electrons scattered from a nickel crystal and formed a diffraction pattern in this experiment.
What was the Davisson–Germer experiment?