photoelectric effect and quantum theory

What was the past belief about energy

physisicts assumed that energy is continous or any orbituary amount of energy could be released in a radiation process

who disorived this belief and what was his counterbelief instead

PLANKS QUANTUM THEORY: Max Planck atoms and molecules only emit energy is discrete quantities known as quanta. He proposed that energy could behave like a particle in the form of tiny energy bundles called quanta.

When did poeple start believing in Planks thoery

after eintsteins work on the photoelectric effect

What are waves vs particles

Waves: are vibrating disturbances that move through space and interfere with each other and can have any value within a range

Particle: Objects with definite boundaries that can bounce off each other when tey collide and can only exist in certain whole number quantities

What are waves characterised by

their length (lamda, their height, and the number of waves that can pass through a certain point in a second (frequency-nu) another important property of waves is their speed

visible light consists of ——- radiation

electromagnetic

what is electromagetic waves or the speed of light and what is the formula for it

speed of light: 3.00 × 10^8 m/s formula c: wave length times frequency

shortest rays are associated with

gamma rays

Shortest waves have —— frequancy and longest waves have ——- frequncy

Shortest waves have highest frequancy and longest waves have lowest frequncy

What did Debroglie suggest/theorise WAVE PARTICLE DUALITY

De Broglie's theory, called wave-particle duality, suggests that particles like electrons can behave like both particles and waves. This means that just as light can act like a wave (with wavelength and frequency), small particles, such as electrons, also have wave-like properties, like a wavelength.

In simple terms: everything, even tiny particles, can act like both a solid object (particle) and a ripple (wave).

Describe the photoelectric effect

The photoelectric effect is when light that has a minimum frequncy/thrshold frequency hits a metal surface and causes it to release electrons. This happens only if the light has enough energy, which depends on its frequency .If the light has a high enough frequency (like ultraviolet), electrons are knocked off the metal.

• If the light has a low frequency, no electrons are released, no matter how bright the light is.

• the number of electrons ejected is proportional to the intensity of the light being emitted, bu the energies of ejectef electrons is not

This effect shows that light behaves like particles (called photons) and that these photons must have enough energy to free electrons from the metal. It helped prove that light has particle-like properties, supporting quantum theory.

describe the highest and lowest wavelengths and frequencies

highest wavelength is radio waves and they have the lowest frquency, lowest wavelengths is gamma rays and they have the highest frequency

Describe UV rays Visible rays and infrared rays

Uv rays: used to look at electronic structure t see where the electrons are found and what they are doing

Visible rays: produced by the motion of electrons wthin atoms and molecules

Infrared rays: used to determine bonds in molecules