Uses of artifical satellites?
• Military uses.
• Scientific research.
• Weather forecasting.
The lower the satellite is from the earth, the wha
• Lower orbit satalites orbit faster around the earth because the gravitational force is stronger.
• Orbital Period speed = Distance from earth
What is gravity?
• Anything with mass exerts a force of gravity.
• The greater the mass the greater the force.
What is a geostationary satellite?
• A geostationary satellite is one which stays over a fixed point across the equator.
• It orbits the earth every 24 hours.
Uses for low polar/high geostationary orbit satell
Low Polar Orbit:
• Weather forecasting.
• Mapping the earth.
High Geostationary Orbit:
• Weather forecasting.
Relative speed of moving objects.
• Two objects moving in the same direction have lower relative speed.
• Two objects moving in the opposite direction have a higher relative speed.
Vector and Scalar quantities?
A vector has both magnitude and direction. A scalar has only magnitude.
How to calculate same/opposite direction vector eq
How to calculate not same/opposite direction vecto
How to use Suvat equations?
What is amplification?
• An amplification gives a signal more energy.
• When waves meet a gap in a barrier, they carry on through the gap.
• The waves spread out into the area beyond the gap.
• The extent of spreading depends on the width of the gap compared with the wavelength of the waves.
What is frequency?
• This is the number of oscillations per second.
What is the ionosphere?
• A region of atmosphere where molecules have been ionised by sun radiation.
How do horizontal projectiles work?
• Horizontal motion is not affected by gravity (vertical motion)
• Horizontal motion is constant in projectiles.
• The path of a projectile is always a parabola.
Example of a parabola:
How to work out momentum?
• Momentum = Mass * Velocity
• Momentum (kg m/s) = Mass (kg) * Velocity (m/s)
• The greater the mass of an object the larger the momentum.
• Without external forces momentum is conserved.
Working out recoil?
1. Recoil m/s = mass of bullet * velocity of bullet / mass of gun
Working out newtons of force?
• Force acting (N) = change in momentum / time taken for change to happen
change in momentum = 100 kg m/s
time taken = 0.2 s
newtons of force = 100 / 0.2 = 500 newtons of force
Note: this only applies when the change in momentum is constant over time.
What frequency waves travel which routes?
• Travel in close contact with the ground.
• Long wave/medium radio waves. (3 MHz)
• Short wave radio waves. (30 MHz)
• Travel up to the ionosphere where they reflect.
• Allows them to travel furthur distances.
• Overcomes the curvature of the earth.
• Microwave signals (3000 MHz)
• Pass through the ionosphere and are reflected off satellites orbiting the earth.
What are transverse waves? How can they be filtere
• All electromagnetic waves are traverse.
• Transverse waves can be polarized to prevent the passing of waves from horizontal sources:
• So you can only see things from light sources you are looking at an angle.
• This reduces glare.
What order is the electromagnetic spectrum in?
What is refraction? Part 1
• Refraction is:
What is refraction? Part 2
• When a wave enters a denser medium, it is slowed down and bends towards the normal.
• When a wave enters a less dense medium, it speeds up and is bent away from the normal.
- As usual, the normal is 90° from the object's surface.
- As the light enters the dense glass, it bends towards the normal.
- As the light leaves the glass to the less dense air, it bends away from the normal.
- The refracted wave is called the emergent ray.
Critical angle and Total internal reflection is wh
• The point after which light will be reflected, rather then refracted is called the Critical angle.
• Light which is reflected back into the glass is called a total internal reflection.
How do fiber optics work?
• Fiber optics work due to cladding.
• The cladding (like mirrors) do not absorb light, they only reflect it.
Snell's Law is what?
• Snell’s law relates the angle of refraction to the angle of incidence as a light wave enters or leaves a more optically dense material.
n = sin i/ sin r
• n is the refractive index of the more dense material such as glass, water etc.
• If you know two of either, n, r or i, then this equation can be worked out.
Convex and Concave lenses do what?
• Convex lenses focus light to converge towards a focal point.
• Concave lenses cause light to diverge and spread out.