Physics (P6) Flashcards
What are ultrasound waves?
Waves above the frequency of what humans can hear
What is the range of human hearing?
20 to 20,000 Hz
Name 3 uses of ultrasound
SONAR (radar)
Pre-natal scans
Crack detection in metal
What are the 2 types of seismic waves
S-waves
P-waves
Describe P-waves
Longitudinal
Can travel through both solid and liquid rock
Provide useful information about the Earth’s core
Describe S-waves
Transverse
Can only travel through solid rock
Travel in curved paths as they cant travel through the Earth’s molten core
What is the law of reflection?
Angle of reflection = Angle of incidence
What type of reflection happens at smooth surfaces?
Specular reflection (all rays reflected at same angle)
What type of reflection happens at rough surfaces?
Diffuse reflection (rays are reflected at different angles)
Why do light rays change direction when they enter a different medium at an angle?
Different parts of the wave front change medium at different times, slowing down at different times and hence changing direction
What is a convex lens?
A lens that is thickr in the middle than at the edges
Parallel light rays that go through the lens converge at focal point
What is a concave lens?
A lens that is thicker at the edges than in the middle
Parallel rays that go through the lens diverge
What is focal length?
The distance from the middle of the lens to the focal point
What is a real image?
Image formed an be seen on a screen
What is a virtual image?
Image formed can only be seen by the person looking through the lens
What is an upright image?
The image faces the same direction as the object
What is an inverted image?
The image in the opposite direction to the object
What is a diminished object?
The image is smaller than the object
What is an enlarged object?
The image is larger than the object
What equation is used for image magnification?
Magnification= Image height/Object height
What is seperation of white light into the spectrum of visible colour?
Dispersion
Which colour of light has the longest wavelength?
Red
Which colour of light has the highest frequency?
Violet
What makes an object appear white?
It reflects all wavelengths of light
What makes a colour appear balck?
It absorbs all wavelengths of light
How does a red filter work?
It absorbs all wavelengths of light except red
It transmits red light
All object emit radiation
True or False?
True
All object absorb radiation
True or False?
True
When do object heat up?
When the rate of energy absorption is higher than the rate of energy emission
When do objects cool down?
When the rate of energy absorption is lower than the rate if energy emission
