A-Levels Physics

Edexcel A-levels - Physics Notes

_______________________________________________________________________________

Notes for PHYSICS UNIT 3:

Edexcel A levels Physics Unit 3 Notes by Niharika on Scribd

_______________________________________________________________________________

Physics Unit 4 Notes (Based on Past Papers)

Uniform Electric Field

Space/area/region where a force acts on a charged particle

 The force is the same at all points Or Field strength is constant Or Field lines equi-spaced

Explain why/how two parallel wires with current in same direction attract

Current in a wire produces a magnetic field

Identifies direction of B field around either wire

(Each) wire is in the magnetic field of the other wire

 A current-carrying wire in a magnetic field experiences a force

Mention of Fleming’s left hand rule (accept motor rule) Or identifies neutral point between wires.

Rutherford gold foil experiment

Observations:

Most alpha went straight through

Some deflected

Very few came straight back Or very few had a deflection > 90o Or 1 in 8000 came straight back Conclusions:

 Atom mainly empty (space)

Charge is concentrated in the centre/in a nucleus/nucleus is charged

Mass is concentrated (at the centre) Or dense/massive nucleus

Role of magnetic field in particle detector

To curve the tracks/paths Or to produce a centripetal force/acceleration Or to allow particles to spiral Or to produce an arc Or to produce circular motion

So that momentum/energy/charge/ velocity/mass can be investigated

What happens to the capacitor when circuit switch is closed

Capacitor charges up Or p.d. across capacitor becomes (equal to) p.d. of cell

Negative charge on one plate and positive charge on the other Or opposite charges on each plate Or movement of electrons from one plate and to the other (around the circuit)

MeV à u

MeV × 10⁶ × 1.6×10^-19 ÷ (3×10⁸)² ÷1.66×10^-27   

3 conservation laws (Particle physics)

è Momentum is conserved

è Charge is conserved

è Mass/energy is conserved

Faraday’s law of electromagnetic induction

The induced e.m.f. (in a conductor) is equal/proportional to the rate of change of (magnetic) flux (linkage) (ε = (−)d(NΦ) /dt)

Explain the path of the ion both between the plates and when it has left the plates

Between the plates there is a force (references to repulsion and attraction are not sufficient)

Gives a downward acceleration Or accelerates towards the negative plate

Constant horizontal velocity Or no forces act horizontally

Outside the plates no (electric) field /force acts Or Outside the plates speed so large that gravitational effect negligible