💡 Physics 💡
Float or Sink
The volume of the object has to be less than (or equal to) the volume of water.
The volume of water is 1g/cm3
Contact and Non-contact forces
Contact forces:
Non-contact forces
Push
Pull
Friction
X-ray
Tension
Magnetic force
Gravity
Electromagnetic
Spring force
Electric force
3 effects forces can have on an object:
Change shape
Change size
Change speed
Circuits
Types of circuit
Parts of a circuit
Questions
This is a parallel circuit: 
This is a series circuit:
Cell:
Ammeter:
Voltmeter:
Bulb:
Switch:
If bulb B went out would the others stay on? 
Bulb A would stay on
Bulb C would stay on
If bulb C went out would the otheres stay on? 
If bulb A went out would the others stay on? 
Bulb C would stay on
Bulb B would go out because Bulb C would use up all the energy coming from the other direction.
Bulb A would stay on
Bulb B would go out because Bulb A would use up all of the energy before it got to Bulb B.
Things that would float:
A feather
Ice
Oil
Things that would sink:
A person
A stone
A pencil
Current and Voltage
Current
Voltage
Current is the amount of electrical charge flowing through a circuit.
Voltage is the name of the electric force that causes electrons to flow between two points in a circuit.
Voltage basically an electric force that causes free electrons to move from one atom to the other
Soundwaves
Speed of Sound and Light
Solids
Liquids
Gases
1,481 m/s
343 m/s
5,120 m/s
Highest and Lowest frequency humans can hear
Transverse and Longitudinal waves
Sound absorption
How are sound waves entering the ear turned into electrical signals to the brain?
How are shadows formed?
Light
300,000,000 m/s
Reflection
Law of Reflection
Refraction
Concave and Convex lenses
Filters and coloured lights
On a reflection from a smooth surface, the angle of the reflected ray is equal to the angle of the incident ray.
A straight beam of light passes through the concave lens and diverges (spreads out) at the other side
For a clear image, all the light rays are reflected off in the same direction (a flat, smooth surface)
For a blurry image, the light rays bounce off the material in different directions (a crumpled surface)
When light bends
It happens when light goes through different mediums e.g. from air to water
The eardrum is connected to the ossicles. The vibrations in the air make the eardrum vibrate, and these vibrations are passed through the ossicles to the cochlea. The signals are passed from the cochlea to the auditory nerve which sends it to the brain. Our brain interprets these signals as sound.
Diffuse reflection
Specular reflection
Highest
Lowest
20,000 Hz
20 Hz
How do vibrating objects cause sound waves to carry energy through the air?
Transverse waves are always characterised by particle motion being perpendicular to wave motion.
A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the direction that the wave moves.
Looks like a spring
Looks like a wave
When an object vibrates it makes the particles around it vibrate as well. Energy is transferred through the vibration and this is how sound travels
This is when the sound waves are absorbed when they come into contact with absorbent materials
Good at absorbing sound: soft furniture; think carpets; curtains
Bad at absorbing sound: smooth flooring; tiles; glass
Shadows are formed when an opaque object is blocking the path of rays of light. The opaque material does not let the light pass through it. The light rays that go around the edges of the material make an outline for the shadow.
A straight beam of light passes through the convex lens and converges (goes into a point) at the other side
Concave lenses are thinner in the middle
Convex lenses are fatter middle
Can make an image magnified
Can make an image minified
Coloured lights
If any colour lights shine on a white ball, the ball will turn the colour of the light
Filters
If you place a red filter in front of a white light the light will turn red
If you put a green filter in front of a white light the light will turn green
Red objects through a cyan light look black
Green objects through a magenta light look black
White light can be split into a spectrum (the rainbow). The main colours of light are red, blue and green.
After those are the secondary colours - yellow, cyan and magenta. Green and red make yellow. Blue and green make cyan. Red and blue make magenta.
If you have a magenta filter only the blue and red are let through as the green is absorbed (blue and red make magenta). If you then have a cyan filter only the blue is let through as the red is absorbed(blue and green make cyan but there isn't any green here).
