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Flashcards in Understanding Processes Deck (65):

How can you half the period of a wave

Double the frequency

Half the wavelength


If 3 identical phasers with an amplitude of A super impose in phase what will the new amplitude be?



What does 1 rotation of a phasor indicate

1 complete wavelength


Why does for exerted by a spring reduce as it recoils?


Tension reduces as it moves forward


Why repeat readings?

Identify as outliers
Mean value is better then any specific value
Reduces uncertainty
Identifys range


How can you work out the probability of a photon arriving?

Intensity * (Phasor Amplitude)^2


How do satellite dishes increase the probability of signal being received?

They have a curved dish to create many paths of equal length


What is the unit for electric field strength and magnetic field strength?


Wb m-2


What makes ceramics brittle?

They contain atoms bonded in random positions leaving no slip planes

Cracks spread as stress is concentrated at the top of the crack


When analysing a graph what should you look for?

Change In gradient
Y intercept


How do you deduce absolute uncertainty of a equation?

What out the maximum possible value and use minus it from the normal value


What equations should be used when formulating equations for projectiles



Give examples of systematic errors

Starting a stop watch at the wrong time
Measuring using a roller without 0 at the end
Measuring the hight at the top of an object instead of at the bottom
Uncalibrated equipment (0 error)


How can you justify number of significant figures?

Find uncertainty
1 s.f above you loose info
1 s.f below you not justified as you round to uncertainty


Why would one use one values uncertainty for an equation but no another values

Compare uncertainties and their effects


How can you calculate thrust?

Thrust = Force + Weight
= Mg + Ma


How can the photo electric effect prove the quantum behaviour of light

Energy required to free an electron

Higher f/Lower Wavelength means higher photon energy

Increasing intensity doesn't mean electrons are emitted if the f is too low

1 photon frees one electron


How can the work function be calculated

E = hf

where e is the work function


What should you say when asked my a calculated value is off

Value used in a equation is too high/low, because reason (diffuclt to measure etc.)


Why would electron diffraction (WL=4nm) be more suitable for studying arrangement of atoms of spacing 0.1nm then light diffraction (WL=600nm)

Wavelength needs to be less than or equal to gap spacing for diffraction

Electron diff is closer to smaller atomic distances


Why is no work done when force is at right angles to direction of motion

Work = Force * Distance (in direction of force)

Distance in direction of force is 0 so no work is done


What is doping of Semi Conductors

When impurities are added to semi conductors to change there properties like conductivity


Why do metals resistance increase as it heats up

As the metal heats up, the atoms inside vibrate,

The Kinetic energy of the atoms is proportional to T (kelvin)

The electrons traveling as charge have the same amount of KE as the atoms, but as they are lighter they vibrate more

This vibration causes collisions in the metal structure, resting the travel of electrons


Why do semi conductors resistance decrease as it heats up

When the semi conductor heats up, the atoms inside vibrate

However, when heated the thermal energy causes electrons to be promoted from the valency band to the conducive band increasing the number of charge carriers

The effect of the promotions is greater then the effect of the vibration, so the resistance decreases


What is an intrinsic material

One that is completely pure without impurities


What is an extrinsic material

One that has had impurities added


What are superconductors

Materials with 0 resistance


Why when calculating a value from an iterative graph why it it always an estimate, and why will a formula produce a different result

There is a lack of precision in the graph, where as:

formula has effectively infinite number of steps

not enough steps in the iterative calculation

time interval too long in iterative calculation

each iteration assumes constant speed


When made up of multiple wavelengths of light, which wavelength will diffract the the most when shone through the slit

The greater the wavelength, the greater the angle of diffraction


What is the first harmonic wavelength on a tube with one open side and one closed



To how many significant figures is an uncertainty

1 s.f


When plotting 1/v to 1/u how can you find 1/f

x intercept



How can you find e/kT using experimental data

Linerise the equation:

Ln N = -e/k(1/T) + Ln N0

Plot the graph of y = mx + c

The gradient is e/kT


How can work done by a moving weight falling into the ground and digging in slightly

GPE = m*g*h where h is the total distance moved


What happens to light patterns when the slit is doubled I n distance

Seperation halfs, intensity doubles


Why are sound changes easier to detect outside then in a laboratory

Less reflection outside, meaning fewer standing waves


A 50w filament build produces the same brightness as a 5w LED. If they are 100% efficient, what does this suggest about the nature of the filament photons

Most/45W of the output of the filament lamp is not visible

Filament emits photons of lower frequency


How can you convert watt hours to joules

Multiply it by 60 squared


How can you find the curvature of waves leaving a lens

Curvature before + Power of lens


How can you find total conductance of 2 components in series and parallel

Series: 1/Ca+1/Cb=1/Ct
Parallel: C1 + C2 = Ct


How can you compare compression strength and tension strength

Stress at Tension BP/Stress at Compression BP


How can you calculate spread

Spread is half the range


How can you calculate an outlier

An outlier is greater or less than 2x the range from the mean


What are the equations for voltage on a charging and discharging capacitor

Charging: V=Vo (1-e^(-t/RC))
Discharging: V=Vo e^(-t/RC)


What are the equations for current on a charging and discharging capacitor

Charging: I=Io e^(-t/RC)
Discharging: I=Io e^(-t/RC)


What are the equations for charge on a charging and discharging capacitor

Charging: Q=Qo (1-e^(-t/RC))
Discharging: Q=Qo e^(-t/RC)


What is the time constant for a charging or discharging capacitor


Charging: The time taken for the change on the capacitor to reach (1-1/e)Qo

Discharging: The time taken for the change on the capacitor to reach 1/e Qo


How can you work out the time taken for a capacitor to reach half charge


Ln 2 = t0.5/RC

t0.5 = RC Ln2


Why might there not be a second order of maxima during differentiation

nλ = dSinΘ

SinΘ is greater then 1

Therefore Θ isn't possible


How can you calculated for exerted by a crash mat if only given work down by falling object and distance of compression

Force = Work/Compression Distance


Why mighty a projectile not reach the max speed/height calculated from SUVAT

Air resistance/Drag provides decreasing force, dissipating energy


How can the number of loops in a wavelength with a frequency X times greater then the fundamental be found?

Fundamental + X Loops


How can you find there power required to accelerate a vehicle

Power = ΔKE/T

= 0.5*M*ΔV^2/t


How can you find force from Kinetic energy

F = Ek/d


How should wavelength be altered to keep the same angled between maxima if slit width is reduced

Reduce Wavelength


How can you work out velocity change between 2 vector

put vector together and find resultant


What equation can be used to improve image contrast

New Value = (Old Value-Old value Minimum)*(Max Possible/Old Range)


Why are capacitor energy equations halved

Energy = Area Under QV Graph
= 1/2 CV


If a bright image is produced by a diffraction gratin, what are the wave crests like on the wavelets

All in-phase


Imagine a trolly connected to 2 springs either side of it. explain why the system is simple harmonic

Force is DP to Displacment
Force id DP to Acceleration - Newtons second Law
Acceleration is in opposite direction to displacement


How does a standing wave form

Identical waves traveling in opposite directions super impose

Leading to constructive interferences (producing antinodes) and destructive interference (producing nodes) if the waves are in phase


If there is no amplitude in the middle of a standing wave, what does it tell you about the waves leaving the source

they are in anti phase as they leave the source


Suggest a practice use for an photo electric cell other then solar pannels

Automatic light sensing switch, however surface needs to be clean and only works for certain wavelengths of light


What effects does alloying a metal have and why

Harder, stiffer, less ductile more brittle as

Dislocations allow layers of atoms to move over each other by breaking one bond at a time producing plastic deformation

Alloying pins dislocation stopping them from travelling through the structure

Allowing for stress to be concentrated in the material making it more brittle


What is yield stress

the point at which plastic deformation occurs