Physics - Energy, heat, light, sound Flashcards
what is energy all about?
the ability of something to do work or cause a change in something else
what are the main aspects of energy?
heat
light
sound
what is heat energy?
form of energy associated with the motion of particles in a substance. when particles in a substance move faster they collide with each other more frequently, causing an increase in temperature which we feel as heat
how is it measured?
in different units depending on the system, most common is calorie which is the amount of heat required to raise the temperature of one ogram of water by 1 degree celsius - others are kelvins, celsius, Fahrenheit
what is a temperature?
measure of the average kinetic energy of particles in a substance that results in how hot or cold the substance is
what is a thermometer?
the instrument used to measure temperatures
define the main ways heat is transferred?
conduction - heat is passed by vibration of particles
convection - transfer of heat in a liquid or gas due to less dense, warmer matter rising and denser cooler matter falling
radiation - movement of heat through electromagnetic wavers which can travel through a vacuum
what is sound?
created by vibrations or movements in a medium, eg air, water or solids. when an object moves bach and forth it creates pressure waves that travel through the surrounding medium, which we call sound
define the main ways sound travels?
longitudinal wave - in which the vibration is in the same direction that the wave is travelling
transverse wave - the vibration is at right angles to the direction the wave is travelling
define the main properties for sound waves
compression - region of high pressure where particles are close together
rarefaction - region of low pressure, particles are far apart
define the main types of lenses that help with light
convex lens - lens that buldges outwards causing light to ray to come together eg magnifying glass
concave lens - curves inwards, causing light to diverge or spread out
define the main terms for light and mirrors
refraction - bending of light as it enters or leaves different substances
refractive index - measure of how easily light travels through a substance
lateral inversion - when an item in a mirror is identical in every way except that it is reversed sideways
what is the law of reflection?
i = r
what is the angle of incidence?
i: the angle an incoming ray makes with the normal
what is the angle of refraction?
r: the angle a refracted ray makes with the normal
what is the angle of reflection?
r: the angle a reflected ray makes with the normal
what is the incident ray?
incoming ray
what is the mirrors normal?
an imaginary line that is drawn at right angles to a surface that light is incident upon
what is light energy and what is it associated with?
form of energy that is associated with electromagnetic waves that we can see eg visible light
define the main properties of light energy
transmitted - when a clear image can be seen through transparent material
reflected - when some light is passed through and is scattered - translucent material
absorbed - no light is transmitted - opaque (blocking the passage of light) material
define opaque
blocking the passage of light
define wavelength
distance between successive peaks
define decibel dB
unit used to measure loudness
define echo
sound that is reflected and heard a second time
