Physics test 1 grade 10 Flashcards
What is the difference between luminous and non-luminous objects?
+ examples
Luminous objects, for example, computers or tvs, emit their own light, while non luminous objects, such as chairs or paper, rely on other sources of light to become visible to humans. The external light source bounces off of the non luminous object and reflects into our eyes, allowing us to see.
Luminous examples: computers, TVs; Non-luminous examples: chairs, paper
Luminous examples: computers, TVs; Non-luminous examples: chairs, paper.
Fill in the blank: Some objects look black because they _______ the light.
absorb
Describe how the reflection at a mirror differs from that at a non-mirror.
Non-mirrors reflect light in all directions due to uneven surfaces, while mirrors reflect light regularly due to their smoothness.
Why do some things appear transparent?
They allow the light to pass directly through them.
What evidence justifies modeling light as a wave?
When water waves pass through a small gap, they spread out and diffract
What is monochromatic light?
Light made up of only one color (one wavelength)
This implies one wavelength.
How fast does light travel?
300,000,000 m/s (300,000 km/s)
How long does light take to travel 1 km?
+ calculation
0.000003 seconds
1/300,000
Why can we call the travel time of light an ‘instant’?
Due to its incredible speed, it seems instantaneous to humans.
How fast does sound travel
343 m / s
Calculation: 1000/3.
Calculation: 1000/3.
If an observer counts 10 seconds between seeing lightning and hearing thunder, how far away was the flash?
3.3 km
Calculation: 10/3.
Calculation: 10/3.
Would the method of measuring distance using light and sound work on another planet?
No, conditions such as temperature and magnetic fields may cause differences.
How long does it take light to reach Earth from Mars? (Mars is 54.6 million km away)
182 seconds or around 3 minutes
Calculation: 54.6 million / 300,000
Calculation: 54.6 million / 300,000.
Fill in the blank: Light can travel through _______.
empty space
What happens to light when it strikes white paper?
It diffuses and bounces off in all directions.
What happens when light strikes black paper?
The paper absorbs it.
What is the speed of light in meters per second?
300,000,000 m/s
What is the wavelength of violet light?
0.0004 mm
What is the wavelength of red light?
0.0007 mm
What does light transfer when it interacts with materials?
Energy
- energy is required to make light
Energy is needed to produce light.
What are the four reflections associated with light
Transmission, diffuse reflection, regular reflection, absorption
examples of non luminous objects
chair, bed, a waterbottle
how do we see non luminous objects
We see non luminous objects because light, including daylight and other sources, bounce off of the object and some of it goes into our eyes. These objects do not emit light, rather reflect it, allowing us to see them.
why do we see colors
Different
wavelengths
are received by our eye and interpreted
by our brain as different colors
White light
White light is made up of a
mixture
of wavelengths.
Evidence that light travels in straight lines
Evidence that light travels in straight lines includes the path of light that a laser or a sunbeam produces
Diffuse reflection
If a surface is rough, diffuse reflection. happens. Instead of forming an image, the reflected light is scattered in all directions. This may cause a distorted image of the object, as occurs with rippling water, or no image at all
Regular reflection
when the light falls on the smooth, shiny surface and reflects entirely within the same angle.
absorption
the process in which light is absorbed and converted into energy
transmission
when light travels through a material completely, like space, air, water, and clear glass
visible light
all wavelengths of light that the human eye can detect
incandescence
production of visible light by an object so hot that it glows
luminescence
production of visible light without heat
types of luminescence
fluorescence, electroluminescence, bioluminescence
fluorescence
a substance absorbes shorter wavelength ultraviolet light and emits light in a visible range of wavelengths (gemstones)
electroluminescence
a substance that gives off light when al electrical current passes through it (neon gas)
bioluminescence
production of light by living things as a result of a chemical reaction(s) (fireflies, jellyfish)
How does light interact with matter
transparent, translucent, or opaque matter
refraction
occurs when light changes direction as it passes into a new medium and changes speed
scattering
occurs when light bumps into tiny particles of matter and spreads out
types of transmission
refraction, scattering
why would matter heat up when light is pointed at it
due to the transfer of energy
transparent matter
matter that transmits light without scattering it
translucent matter
matter that transmits light but scatters it as it passes through
opaque
matter that doesn’t let light pass through
features of light (6)
it is a form of radiation
it travels in straight lines
it transfers energy
it behaves like waves
it travels through empty space (no medium required)
it is the fasted thing
how does light travel
Light exhibits characteristics of both waves and particles, the latter of which are described as packets of energy called photons. These waves, or photons, travel in narrow beams called rays. Only when light rays move from one medium to another, such as from air to water, are their linear paths altered.
what is diffraction
the spreading of waves as they pass through or around an obstacle.
Distance, speed, time triangle
distance
speed x time
when does diffraction increase
as the gap gets closer to the size of the wavelength
LED lights
- stands for “light-emitting diode.” - – - semi-conductor, which gives off visible light when an electric current flows through it.
- used for traffic lights (see Figure below) and also indicator lights on computers, cars, and many other devices.
- very reliable and durable.
Vapor lights
- produces visible light by electroluminescence
- The bulb contains a small amount of solid sodium or mercury as well as a mixture of neon and argon gases. - When an electric current passes through the gases, it causes the solid sodium or mercury to change to a gas and emit visible light.
- bright and reliable
neon
- A neon light produces visible light by electroluminescence. In this process, neon or some other gas gives off light when an electric current passes through it
- When electricity passes through the gas, it excites electrons of neon atoms, and the electrons jump to a higher energy level. As the excited electrons return to their original energy level, they give off visible light.
