Science Flashcards
What’s the formula for pressure?
P = f / a
f = force a=unit area
What is the unit for pressure?
Pascals
What is the formula for a right triangle?
AB / 2
A = height b= base
What are light sources referred to as?
They are reffered to as luminous.
What are the three ways light can affect objects?
It can be transmitted, reflected or absorbed.
What happens when an object absorbs light?
It is converted into thermal energy and heats the object up.
Does light need a medium?
No
What happens to light that is far away?
It spreads out and thus gets dimmer.
What is the initial ray of light called in a reflection?
Incident ray
What is another name for a flat mirror
A plane mirror
What are the two types of images?
Virtual and real
What is a real image?
Its an image you don’t need to look through anything to see.
What is the law of reflection?
It states that angle of incidence = angle of reflection
What is a laterally inverted image?
Its an image that is flipped to be opposite of the object.
What is refraction?
It is the bending of light
How do you calculate angle of refraction?
Same as reflection but on the other side of the material.
Do refracted objects appear higher or lower than they are?
Higher
What does the speed in different materials depend on?
It depends on the density of the material.
How do you calculate the refractive index?
Speed of light in a vacuum / speed of light in the medium
How many times does light refract in an object?
2 times
What are the colours of the white light spectrum?
Red, orange, yellow, green, blue, indigo and violet
What is the process of splitting white light into a spectrum called?
Dispersion
Why can you only see a rainbow when the sun is behind you?
Light reflects backwards off of raindrops so can only be seen behind.
How can you recombine the light spectrum?
By using another prism upside down.
What are the three primary colours?
Red, green and blue
How do televison coloured screens work?
They work by emitting primary colours and placing a filter over them.
What happens to the image formed on the retina?
It is upside down
Why would an object look red?
It’s because the object absorbed all other forms of light except red which it reflects.
Is light a wave or a particle?
Wave-particle
What transfers signals from your eye to your brain?
The optic nerve
Where is the retina?
At the back of the eye
What is the muscle that controls the size of the pupil called?
The iris
What is the hole light goes in called?
The pupil
What is the transparent outer layer of the eye called?
The cornea
What part of the eye focuses light on the retina?
besides the cornea
The lens
What is the critical angle in refraction?
It’s the angle where refracted light is at 90 degrees to the normal
What is internal reflection?
It’s when the refracted angle exceeds the critical angle
What is the name of the effect which allows raindrops to cause a rainbow?
Dispersion
What is a regular reflection?
It’s when light reflects off of a smooth surface.
Does a blue filter absorb or let blue pass through?
It lets blue pass through and absorbs everything else.
What happens if you remove a magnet from steel after putting it near one?
The steel remains magnetized.
How can you demagnetize an object?
By heating it up or hitting it with a hammer
How could you see a magnet?
By using a plotting compass or iron filings
What is an electromagnet?
It’s a magnet that is powered by electricity.
What can make an electromagnet stronger?
Coils
What influences the strength of an electromagnet?
- The number of turns of the coil
- The voltage
- The type of core (magnetic materials are better)
What is the advantage of an electromagnet over regular magnets?
You can turn it on and off
What are relays?
They’re a device to use current in one circuit to power another circuit.
usually when it’s too dangerous to handle normally
What are some uses of electromagnets?
Relays, fire doors, electric bells and MRI machines
What is the difference between primary and secondary energy sources?
Primary comes from nature while secondary comes from refined primaries.
What will happen if you move a magnet towards a voltmeter?
It will induce a voltage.
What will happen if you move a South magnet towards a voltmeter instead of North?
The direction of movement for the coil will be reversed.
