harder Flashcards
How do gases exert pressure?
The particles move in high speed , random directions.
Collision with the walls of the container exerts a force- a net force on the inside of the container (surface) determines the pressure
How does temperature affect pressure?
The more temperature, the faster the particles move, the more frequently the particles collide with the container walls, the more force is exerted resulting in more pressure.
what is the atmospheric pressure on earth?
100 kilo pascals
100,000 pascals
Describe up thrust
A force that occurs whenever a body is immersed within a fluid.
Because of a pressure difference between the top and bottom fluid
What happens when the atmospheric pressure is greater inside a ballon that it’s surroundings?
What is inertia ?
How difficult it is to change the velocity of a body.
The greater mass, the greater interia
Define momentum
How difficult it is to stop a moving body. The two factors affecting this are mass and velocities.
(A vector value)
What is the deforming force?
Stretching , compressing or bending a body to change the shape
What does it mean for a material to be brittle?
It has all linear sections, will snap instead of stretching after the elastic limit.
What is a moment?
The moment of a force is the measure of its turning effect, about a pivot.
the greater the moment , the easier it is to rotate a body
What is formula for moment’s?
M= d ✖️force
d is the perpendicular distance from the pivot to the the line of action of force (m)
How can the moment of the force be increased?
🟢Increasing the size of the force
🟢increasing the perpendicular distance from thepivot
What it the mechanical advantage of gears?
Output cog radius➗input cog radius
Largest value always as the numerator
What happens to a car when travelling up hill? (Gears)
🟢you change to a lower gear 🟢the means input gear is a small gear is connected to a larger gear 🟢a input larger moment 🟢an output smaller moment 🟢causing the wheel to turn more slowly
*Large mechanical advantage
What is the symbol for a diode?
A circle with a triangle , line at the end pointing in the direction of current
What is the symbol for an LEd
The symbol of a diode with two arrows coming out of the circle
How much charge does an electron carry?
1.6 ✖️10^-19 coulombs
Describe the IV graph for a filament light bulb
🔺The resistance increases with p.d
🔺As the resistance increases as it is getting hotter
🔺Non - linear circuit element
What is a sensor circuit?
A circuit that turns a component on or off automatically in response to external stimuli
Why are their differences in voltage between the wires?
The cell/ battery creates chemical reactions which bunch up the electrons in places of the wire. So the electrons will travel from a high point to a low point , creating a p.d
What is magnetic flux density?
The number of lines of force passing though a unit of area of material
Measured in Tesla’s
Newton per amp meter
Why does increasing the current increase the force ?
motor effect
- Magnetic field lines exist around a wire with a current
2. The larger the current the greater magnetic fie,s strength in the interaction between the wire and permanent magnet
What is the generator effect (electromagnetic induction)?
When a conductor cuts the magnetic field lines of a magnet, a potential difference is induced across the ends of the conductor
Describe the generator effect:
🟣wire with no current , within a magnetic field is experiencing a force
🟣this force is perpendicular to the direction of magnetic field
🟣as the wire cuts field lines, electrons are accelerated inducing a p.d
🟣this creates a current
What happens when the motor and generator effect take place together?
The force and current produced by the motor effect counteracts the generator effect.(law of conservation of energy)
State Lenz’s Law
The direction of the induced p.d is such that it opposes the change producing it
How do you increase the induced p.d of an alternator?
🟣rotate coil faster (more field lines cut per second)
🟣stronger magnetic field (field lines closer together, so more cut)
🟣more coils
* doubling frequency
What are transformers?
Devices that use a.c in the primary circuit to induce an a.c in the secondary current
How do transformers work?
Describe the difference between step up and step down transformers
What is the normal line , of a wave diagram ?
The mean position of the particle
What is the amplitude of a wave diagram ?
The maximum displacement of the particle from it’s mean position
Describe the general specifics of electromagnetic radiation:
🟣transverse waves (light waves )
🟣do not require a medium to travel
🟣produced by vibrating ,charged particles
What are the differences between electromagnetic waves and sound waves ?
Describe UV waves
Very very slightly ionising m could possible cause cancer .
Moderately penetrate the earth’s atmosphere, but not the skin.
What is activity?
The number of nuclei that decay per second
How do you plot activity?
Divide mass by 2 , then plot this point .
Divide the new mass by 2 and then plot this point
