Science Grade 7 Semester 1 Examination Vocabulary Flashcards
Prokaryotic Cells/Prokaryotes
Cells without a nucleus
Eukaryotic Cells/Eukaryotes
Cells with a nucleus
How is sound created?
Sound is created through small vibrations, which transmit energy
What has to be there for there to be sound?
A source of the sound, a medium which the sound travels though and the receiver which receives the sound
How is loudness of sound determined?
It is determined by the intensity of sound waves. Intensity is the amount of energy in sound waves
How is the intensity of a sound/loudness measured
It is measured in decibels (db)
How is the intensity of a sound determined?
Intensity results from 2 factors: amplitude of sound waves and how far the sound traveled from the source
Why do sounds get quieter the further they travel?
The sound waves spread out as they travel further from the source because the area covered by the sound waves becomes larger.
What is pitch?
The pitch of a sound is how high or low it is
How is pitch determined?
Frequency of sound waves determines the pitch of sounds
What is infrared light?
Infrared light is red light that is beyond the visible range of light waves for humans. It can be felt as heat and can be detected using special technology
What is ultraviolet light?
Ultraviolet is light that has a shorter wavelength than the human eye can see. It is dangerous because it has so much energy that too much exposure to skin can cause sunburns or skin cancer.
What is resonance and what does it do?
Resonance happens when something vibrates due to sound waves of certain frequency. Resonance amplifies a sound
What is refraction?
Refraction is the bending of a ray of light when it passes at an angle from one medium into another. The density of the mediums are different so the speed of the ray will change.
What is the law of reflection?
The law of reflection is that the light on a regular reflection surface (e.g. a plain mirror) has the same angle of reflection as the angle of incidence ( r = i )
