Physics - Energy, heat, light, sound

Question 1

what is energy all about?

Answer 1

the ability of something to do work or cause a change in something else

Question 2

what are the main aspects of energy?

Answer 2

heat
light
sound

Question 3

what is heat energy?

Answer 3

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

Question 4

how is it measured?

Answer 4

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

Question 5

what is a temperature?

Answer 5

measure of the average kinetic energy of particles in a substance that results in how hot or cold the substance is

Question 6

what is a thermometer?

Answer 6

the instrument used to measure temperatures

Question 7

define the main ways heat is transferred?

Answer 7

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

Question 8

what is sound?

Answer 8

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

Question 9

define the main ways sound travels?

Answer 9

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

Question 10

define the main properties for sound waves

Answer 10

compression - region of high pressure where particles are close together
rarefaction - region of low pressure, particles are far apart

Question 11

define the main types of lenses that help with light

Answer 11

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

Question 12

define the main terms for light and mirrors

Answer 12

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

Question 13

what is the law of reflection?

Answer 13

i = r

Question 14

what is the angle of incidence?

Answer 14

i: the angle an incoming ray makes with the normal

Question 15

what is the angle of refraction?

Answer 15

r: the angle a refracted ray makes with the normal

Question 16

what is the angle of reflection?

Answer 16

r: the angle a reflected ray makes with the normal

Question 17

what is the incident ray?

Answer 17

incoming ray

Question 18

what is the mirrors normal?

Answer 18

an imaginary line that is drawn at right angles to a surface that light is incident upon

Question 19

what is light energy and what is it associated with?

Answer 19

form of energy that is associated with electromagnetic waves that we can see eg visible light

Question 20

define the main properties of light energy

Answer 20

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

Question 21

define opaque

Answer 21

blocking the passage of light

Question 22

define wavelength

Answer 22

distance between successive peaks

Question 23

define decibel dB

Answer 23

unit used to measure loudness

Question 24

define echo

Answer 24

sound that is reflected and heard a second time

Question 25

define frequency

Answer 25

number of waves passing a point every second

Question 26

define Hertz Hz

Answer 26

a unit used to measure frequency

Question 27

define ultrasound

Answer 27

name given to sound waves with frequencies above the hearing range

Question 28

define infrasound

Answer 28

sounds produced by waves of very low frequencies than 20 Hz