ines whether electrons are eventually emitted from a metal?","back":"The intensity of the light (energy should accumulate over time).","points":1,"mcqOptions":[{"text":"The intensity of the light (energy should accumulate over time).","correct":true,"explanation":"Classical wave theory treats light energy as continuously distributed, so greater intensity transfers energy faster and even low-frequency light should eventually provide enough energy for emission."},{"text":"The frequency of the light (each electron absorbs one packet of energy).","correct":false,"explanation":"Energy arriving in discrete packets determined by frequency is the photon model, not classical wave theory. Classical theory instead predicted that intensity controls energy transfer and accumulation."},{"text":"The polarisation of the light (electrons must align with the electric field).","correct":false,"explanation":"Polarisation can affect how electromagnetic waves interact with a surface, but classical theory did not make it the deciding condition. It predicted eventual emission based on light intensity."},{"text":"The angle of incidence of the light (energy must strike the surface normally).","correct":false,"explanation":"Normal incidence is not required for photoelectron emission. Classical wave theory predicted that sufficiently intense light would transfer enough energy over time, regardless of its frequency."}]},{"id":"1ea0684c-c20d-4f15-ab20-7f3ba1c337e9","cardType":"basic","front":"What observation regarding the timing of emission contradicted classical wave theory?","back":"Emission is instantaneous above the threshold frequency, even for very dim light.","points":1,"mcqOptions":[{"text":"Emission is instantaneous above the threshold frequency, even for very dim light.","correct":true,"explanation":"Electrons are emitted without a measurable delay when individual photons have sufficient energy. This remains true at low intensity, when fewer suitable photons arrive per second."},{"text":"Emission occurs after a long delay above the threshold frequency when the light is very dim.","correct":false,"explanation":"A delay would support the classical idea that electrons gradually accumulate energy. Experimentally, emission is instantaneous above the threshold frequency, even when the incident light is very dim."},{"text":"Emission is instantaneous below the threshold frequency when the light is sufficiently bright.","correct":false,"explanation":"Greater intensity increases photon number, not individual photon energy. Below the threshold frequency no electrons are emitted, whereas emission begins instantaneously when the threshold is exceeded."},{"text":"Emission occurs after a short delay below the threshold frequency when the light is sufficiently bright.","correct":false,"explanation":"This reflects the classical energy-accumulation prediction, but experiments show no eventual emission below threshold. Above the threshold frequency, electrons are instead emitted instantaneously, even with dim light."}]},{"id":"e457ed08-ad0b-4263-a038-9bb8c35bc71b","cardType":"basic","front":"How does classical wave theory fail to explain the existence of a threshold frequency?","back":"It predicted that any frequency should eventually liberate electrons if the light is bright enough.","points":2,"mcqOptions":[{"text":"It predicted that any frequency should eventually liberate electrons if the light is bright enough.","correct":true,"explanation":"Classical theory links transferred energy to intensity rather than photon frequency. It therefore predicts that sufficiently intense light of any frequency should eventually give electrons enough accumulated energy to escape."},{"text":"It predicted that only high frequencies should eventually liberate electrons if the light is bright enough.","correct":false,"explanation":"Restricting emission to s

The photoelectric effect

The photoelectric effect Flashcards

The photoelectric effect

The photoelectric effect Flashcards