# Shared Flashcard Set

## Details

OCR - AS physics Unit 2 - Electrons waves and Photons
for all of you AS students who are thourouhly terrible at physics and need a bit of a nudge in the right direction like me
47
Physics
Not Applicable
01/16/2014

Term
 Define a Coulomb
Definition
 quantity of charge which passes when a current of 1 ampere passes for a time of 1 second
Term
 What is the value of the elementary charge?
Definition
 1.6 x 10^-19
Term
 State Ohm's Law
Definition
 At constant temperature, the voltage of a conductor is directly proportional to it's current
Term
 Define Charge
Definition
 Current x time
Term
 Define Current along with it's formula (2 points)
Definition
 Rate of flow of charge Q = I * t
Term
 Define Ampere
Definition
 The fundamental SI unit of Current
Term
 State Kirchhoff's first law, and is a consequence of ____
Definition
 the sum of current entering a junction is equal to the sum of currents leaving a junction-consequence of conversion of charge
Term
 State Kirchhoff's second law, and is a consequence of ____
Definition
 In any closed circuit, the sum of all p.d.s is equal to the sum of all e.m.f.s -consequence of conservation of charge
Term
 Define resistance
Definition
 property of a component that regulates the electrical current though it measured in ohms
Term
 Define Electromotive force
Definition
 is the energy transferred per unit charge when one type of energy is converted into another form of energy
Term
 Define Potential difference
Definition
 is the energy transferred per unit charge when electrical energy is converted into another form of energy
Term
 Define Resistivity
Definition
 is defined as p= RA / l where;p= resistivityR= cross sectional areaA= cross sectional areal= length of wire
Term
 Define Internal resistance
Definition
 resistance of an e.m.f. source (due to the chemicals in the cell or battery)
Term
 Define terminal p.d.
Definition
 total p.d. across the load external resistance
Term
 I-V characteristic of a LED
Definition
 - near infinite resistance before 0.6 V- resistance decreases as voltage increases after 0.6 V
Term
 I-V characteristic of a Filament lamp
Definition
 Resistance is proportional to voltage until it reaches 1.5 V wherein the resistance increases as the Temperature increases
Term
 I-V characteristic of a fixed resistor
Definition
 straight diagonal line that goes through the origin
Term
 Define Power
Definition
 Rate at which work is done
Term
 Unit of:a. powerb. energy
Definition
 a. watts b. joules
Term
 Define a progressive wave
Definition
 waves that move away from a source
Term
 Define transverse waves
Definition
 the direction of oscillation is perpendicular to the direction of propagation
Term
 Define longitudinal wave
Definition
 direction of oscillation is parallel to the direction of propagation
Term
 Define Displacement
Definition
 distance from a point in the wave to the mean value
Term
 Define Amplitude
Definition
 maximum displacement from the mean
Term
 Define Frequency
Definition
 the amount of complete oscillations within a given unit of time
Term
 Define wavelength
Definition
 smallest distance between one point on a wave and the identical point on the next wave
Term
 Define Period
Definition
 Time taken to complete one full oscillation
Term
 Define Phase difference
Definition
Term
 Relationship of INtensity and Amplitude
Definition
 Intensity is directly proportional to amplitude^2
Term
 Define Reflection
Definition
 occurs when a wave bounces back from the surface of an obstacle
Term
 Define Refraction
Definition
 occurs when the wave enters a different medium with a higher density than air and changes direction and speed
Term
 Define Diffraction
Definition
 The spreading of waves when they pass though a aperture or around an object
Term
 Define Polarisation
Definition
 process of converting an unpolarised wave into a polarised wave
Term
 How would you conduct a experiment to see the polarisation of microwaves (3 marks)
Definition
 Two polarising filters placed between transmitter and receiver that are facing each other . Start with both filters being parallel to each other, which allows microwaves through freely, then twist the second filter through 90 degrees and observe the drop in detection until 0 . This shows that the microwaves must have been polarised through the first filter, otherwise detection would have been equal throughout the rotation. 
Term
 Describe Malus's law
Definition
 A physical law that describes the cgane in intensity of a wave passing though a polaroid analyser
Term
 Define Interference
Definition
 the superposition of 2 or more waves that result in a new wave pattern
Term
 How can a wave be coherent?
Definition
 coherent waves arewaves that have the same frequency and a constant phase difference
Term
 Constructive interference
Definition
 occurs when two waves that are in phase reinforce
Term
 destructive interference
Definition
 occurs when two waves that are antiphase cancel each other out
Term
 Define monochromatic
Definition
 Light that has the same wavelength
Term
 How is a stationary wave formed?
Definition
 A stationary wave is formed when two coherent waves that are travelling in opposite directions superpose
Term
 what is a node?
Definition
 a node is a spot where the displacement is always zero due to destructive interference
Term
 What is an antinode
Definition
 an antinode is a spot where the amplitude is maximum due to constructive intereference
Term
 Define Threshold frequency
Definition
 Frequency of elctromagnetic radiation that will result in an emmision of photoelectrons from a specified metal surface
Term
 Define Electron volt
Definition
 Energy charge of an electron as it moves through a potential difference of 1 volt
Term
 Define Work function
Definition
 energy required to move an electron from it's surface
Term
 Stopping potential
Definition
 The Potential difference required to stop the movement of electrons in a closed circuit
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