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Flashcards in Understanding Processes Deck (65):
1

How can you half the period of a wave

Double the frequency

Half the wavelength

2

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

3A

3

What does 1 rotation of a phasor indicate

1 complete wavelength

4

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

Friction

Tension reduces as it moves forward

5

Why repeat readings?

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

6

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

Intensity * (Phasor Amplitude)^2

7

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

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

8

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

NC-1

Wb m-2

9

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

10

When analysing a graph what should you look for?

Gradient
Change In gradient
Y intercept

11

How do you deduce absolute uncertainty of a equation?

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

12

What equations should be used when formulating equations for projectiles

SUVAT

13

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)

14

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

15

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

Compare uncertainties and their effects

16

How can you calculate thrust?

Thrust = Force + Weight
= Mg + Ma

17

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

18

How can the work function be calculated

E = hf

where e is the work function

19

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.)

20

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

21

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

22

What is doping of Semi Conductors

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

23

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

24

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

25

What is an intrinsic material

One that is completely pure without impurities

26

What is an extrinsic material

One that has had impurities added

27

What are superconductors

Materials with 0 resistance

28

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

29

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

30

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

λ/4

31

To how many significant figures is an uncertainty

1 s.f

32

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

x intercept

1/v=0+1/f

33

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

34

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

35

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

Seperation halfs, intensity doubles

36

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

Less reflection outside, meaning fewer standing waves

37

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

38

How can you convert watt hours to joules

Multiply it by 60 squared

39

How can you find the curvature of waves leaving a lens

Curvature before + Power of lens

40

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

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

41

How can you compare compression strength and tension strength

Stress at Tension BP/Stress at Compression BP

42

How can you calculate spread

Spread is half the range

43

How can you calculate an outlier

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

44

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)

45

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

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

46

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)

47

What is the time constant for a charging or discharging capacitor

t=RC

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

48

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

2=e^(t0.5/RC)

Ln 2 = t0.5/RC

t0.5 = RC Ln2

49

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

nλ = dSinΘ

SinΘ is greater then 1

Therefore Θ isn't possible

50

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

51

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

Air resistance/Drag provides decreasing force, dissipating energy

52

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

Fundamental + X Loops

53

How can you find there power required to accelerate a vehicle

Power = ΔKE/T

= 0.5*M*ΔV^2/t

54

How can you find force from Kinetic energy

F = Ek/d

55

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

Reduce Wavelength

56

How can you work out velocity change between 2 vector

put vector together and find resultant

57

What equation can be used to improve image contrast

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

58

Why are capacitor energy equations halved

Energy = Area Under QV Graph
= 1/2 CV

59

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

All in-phase

60

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

61

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

62

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

63

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

64

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

65

What is yield stress

the point at which plastic deformation occurs