Term
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Definition
| Electrons move around circuit from one plate to the other until the PD across the capacitor = the supply PD |
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Term
| Circular motion: weightlessness |
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Definition
| You feel weightless when the reaction force = 0 - so going over a humpback bridge or over a vertical loop, at the top, mg=mv2/r |
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Term
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Definition
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Term
Electric Field:
Uniform Field |
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Definition
Region where a force acts on a charged particle
The force is the same at all points |
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Term
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Definition
Cathode is heated (by a current)
causing Thermionic emission |
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Term
| Faraday: Peak in voltage when a current in a coil is turned off: Faraday's Law |
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Definition
Current in coil Generates a magnetic field
turning off current causes a rapid change in flux
Inducing a large emf |
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Term
| Faraday: Why you get a large emf |
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Definition
| Lots of coils means large flux linkage |
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Term
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Definition
| Particle is moving fast - mass will be larger due to moving near the speed of light |
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Term
| Induction: Magnet not moving |
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Definition
Magnetic field from electromagnet changes (due to AC current)
Flux through coil/wire changes
Induces EMF |
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Term
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Definition
Magnet moves
Flux through coil/wire changes
Induces EMF |
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Term
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Definition
induced current/emf (direction)
Opposes the change (that produced it) |
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Term
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Definition
| Gev/c2 to kg: Simply convert the eV to Joules (1eV=1.6x10-19J) and then divide by c2 (because mass=E/c2) |
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Term
| Momentum: Particles leave at right angles if they've the same mass |
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Definition
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Term
| Momentum: Rocket propulsion |
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Definition
Momentum conservation
Total/initial momentum = 0
Momentum of material ejected equal momentum of rocket
Rocket moves in opposite direction |
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Term
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Definition
Current in a wire creates a magnetic field
Magnetic field is around wire.
If this interacts with another magnetic field there will be a force - Fleming's LHR gives direction of force |
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Term
| Particle Accelerators - size of force |
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Definition
| Electric field applies a force to the charged particle (proton) as F=Eq |
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Term
| Particle accelerators :Steering Particles (cyclotron) |
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Definition
E-Field: Provides force (as F=Eq) to accelerate the charges across gap between Dees
B-Field: Provides a centripetal force on the charge to move it in a curve
The E-Field reverses each time the charge enters a Dee |
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Term
| Particle Detectors : Why a magnetic Field? |
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Definition
To provide a centripetal force to cause the particles to travel in curved paths.
…so that you can investigate their momentum/mass/KE |
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Term
| Particle Detectors: B-Fields |
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Definition
• provides a centripetal force
• Direction of force/curvature/deflection indicates (sign of) charge.
• momentum/speed/mass found from radius/curvature
• r = p/BQ Or Bqv = mv2/r |
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Term
| Particle Detectors: E-Fields |
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Definition
• can be used to accelerate or deflect particles
• direction of force (deflection)indicates (sign of) charge.
• a = EQ/m |
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Term
| Particle Tracks - uncharged particles |
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Definition
Uncharged particles leave no tracks
The decay of an uncharged particle will be see as two or more tracks appearing from "nowhere" |
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Term
| Particle Tracks: Conservation |
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Definition
Curve in opposite directions: charge conserved
Two tracks appearing: charge conserved (initial particle, charge=0 - new particles +1 + -1 = 0)
Particles moving in opposite directions: conservation of momentum(depending on context) |
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Term
| Particle tracks: Curvature |
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Definition
| The radius of curvature gets less as it slows down |
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Term
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Definition
| More curved, particle is slowing as it loses energy. |
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Term
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Definition
| A vacuum so that the particle does not collide with gas molecules |
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Term
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Definition
Same mass, opposite charge, lepton number, baryon number
(Can be stored in an electric field if the particle is charged) |
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Term
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Definition
Force acts at right angles to direction of ion movement
This force provides a centripetal force |
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Term
| Particles Decay: Conservation of properties |
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Definition
Momentum conserved
Charge conserved
Energy / mass conserved
Baryon Number/Lepton Number |
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Term
| Particles: Conservation of Momentum |
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Definition
| When a particle decays particles leave in all directions because * initial momentum is zero * so sum of momentum of fragments = zero to conserve momentum |
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Term
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Definition
Observations
Most alpha went straight through
Some deflected
Very few came straight back
Conclusions
Atom mainly (empty) space
Nucleus contains most of the mass
Nucleus very small
Nucleus positively charged |
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Term
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Definition
| Draw the vectors "Nose-to-tail" - the resultant vector is the vector from the start of the first to the end of the last |
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