Stewart Flashcards
Define an electric field.
A region around a charged particle or object within which a force would be exerted on other charged particles or objects.
Draw the electric field around a single positive charge.
An electric field exists between two parallel plates connected to a potential difference. Draw the field between the plates.
The eclectric field is uniform (space between the lines) between the plates and bulges outwards at the edges.
Discuss the use of the electric field between two parallel plates.
An electric field strength is determined by either
- finding the force acting on a charge placed at a point.
- voltage between the plates divided by the distance between the plates
Recall the effect of ultraviolet light in Hertz’s experiment.
Hertz observed that the gap in the detector could be made larger and still generate sparks when the radiation from the transmitting spark directly into the gap in the detecting loop. Hertz did not recognise that the unltraviolet component in the transmitter spark removed free electrons from the surface of the metal, allowing the discharge (spark) to occur across a wider gap.
Define the photoelectric effect.
The photoelectric effect is the release of electrons from a metal surface exposed to electronmagentic radiation.
Recall Planck’s quantum hypothesis.
Describe what led Planck to propose this hypothesis.
In order to explain the frequency distrubution of radiation from a hot cavity (black body radiation) Planck proposed the assumption thatr the radiant energy could exist only in discrete quanta which were propotional to the frequency.
