Nature of Light: Wave vs. Particle Debate

Debate on light's nature: wave vs. particle theories persisted for centuries.
Isaac Newton favored the particle theory, believing light travels in straight lines and couldn’t propagate in a vacuum.
Christian Huygens opposed, explaining wave-related phenomena like fuzzy shadows due to wave interactions.
The Double Slit Experiment by Christopher Young confirmed waves prevailed by creating diffraction patterns.
Albert Einstein revived particle theory through the photoelectric effect, showing electrons are ejected based on light's frequency, not intensity.
Light exhibits wave-particle duality, incorporating properties of both particles and waves.
Louis de Broglie extended duality to all particles with mass.

Important properties include intensity (brightness), direction, frequency (color), and polarization.
Investigated lab phenomena include straight-line travel of light, reflection from mirrors, and color production.

Reflection occurs when light bounces off reflective surfaces; characterized by the law of reflection (incident angle equals reflected angle).
Refraction is the bending of light as it transitions between different media, affected by the density of those media.

Lenses are optical devices that use refraction to form images, categorized into convex and concave lenses.
Convex lenses focus light rays to a point, enabling applications in telescopes and microscopes.
Concave lenses disperse light rays, used in corrective eyeglasses for nearsightedness.
Ray diagrams illustrate image characteristics using three principal ray paths, defining real vs. virtual image concepts.

Diffraction involves the spreading of light as it passes through an aperture or around obstacles.
Patterns of light and dark areas arise from constructive (peaks overlap) and destructive (peak meets trough) interference.
Diffraction patterns can be observed through slits comparable to light's wavelength.

Light is classified as an electromagnetic wave with specific frequencies determining color.
Higher frequency waves appear blue, while lower frequency waves appear red; color-filter experiments illustrate this principle.

Electric current results from the flow of free electrons, measured in amperes; exists as direct current (DC) with fixed direction or alternating current (AC) which varies over time.
In electrolytes, current arises from charged ions; in gases, from ionization.

Circuits form complete loops allowing electron flow; components act as resistors, consuming energy.
Resistance decreases current, illustrated by Ohm’s law, which states current varies inversely with resistance.

Voltage is the electrical energy provided to circuits, initiated by sources like batteries or generators converting various energy types.
OHM’s law related resistance, current, and voltage, revealing their interdependence.

Series circuits connect components in one path, splitting voltage while maintaining consistent current.
Parallel circuits allow current division among branches with equal voltage across each.

Resistance opposes current flow, measured in ohms; affected by length, cross-sectional area, and temperature of conductors.
Joule's law explains energy conversion to heat in resistive components.

Voltage indicates potential work from charged particles, analogous to pressure in a system.
Charge density influences voltage, expressed in joules per coulomb (volts).