Flashcards in Physics In Action Deck (53):

1

## Define Ionisation

### When particles loose some electrons to become positively charged ions

2

## How can you find resistance from a voltage current graph

###
The gradient if its a straight line through the origin

V=IR if not

3

##
How can you use a polarising filter to deduce whether a wave is polarised

###
Rotate the filter 90 degrees, and watch intensity fall from max to min

The min intensity will show how much the light was polarised

4

## How does a Lens Work?

###
Adds curvature to wave fronts focusing them to a point

Lense is thinner at the ends so the edges are curved for less time, cause of the edges to curve

5

## What is plastic behaviour

### When an object loses the ability to return to its original shape

6

## What is machinability

### Ability for a material to be deformed by compression without being torn or cracked

7

## What is the PD-Current graph for a cell with internal resistance, and how can you use it to find internal resistance and EMF of the cell

###
Graph has positive y intercept with a negative consistent gradient

The gradient is the internal resistance

The y intercept is the EMF of the battery

8

## what is the equation for Youngs 2 slit experiment and the diffraction grating

###
nλ=dsinΘ

where λ is wavelength

n is the order of maxima

Θ is the angle of the maxima

9

## What is the path difference at the nth maxima of a diffraction

### nλ

10

## Define Brittle

### The tendency for a material to fracture under a force

11

## Define Ductile

### The ability for a material to be drawn or stretched

12

## Define Hardness

### The ability for a material to withstand indentation, abrasion, or scratching

13

## Define Stiffness

### the ability for a material resistance to changes in size and/or shape. A stiff material has a high YM and is difficult to bend

14

## How can the magnification of an image be calculated

### M = v/u

15

## How can you work out the size of an image through a lens

### Image Size = Object Size * Magnification

16

## How can you describe a materials behaviour as its stretched passed its elastic limit to its breaking point?

###
Large increase in strain for small increase in stress

Gets stiffer

Up to x times original length

17

## Why are long chain molecules easy to stretch past the elastic limit

###
Long chain molecules are amorphous (crumpled)

Monomers rotate (unfold) and become crystalline

Intermolecular bonds break

18

## Whats the difference between polarised and unpolarised light

###
Waves are transverse (oscillations are perpendicular to direction of travel)

Unpolarised: Vibrations in all possible directions

Polarised: Vibrations in one direction

19

## Define Strong

### strong Strong materials require a large force per unit area to fracture

20

## How can you find a signals resolution

### Resolution = P.D Range/No. Levels

21

## Why are metals ductile and glasses brittle

###
Metals have a regular structure containing dislocations allowing for slip. The structure is bonded using positively charge ions surrounded by a sea of negative electrons which are non directional so the structure can be bent

Glasses have an irregular structure of atoms bonded in random locations meaning no slip planes, causing stress to build and micro cracks

22

## After excitation, during relaxation, how is the energy emitted as the electron falls an energy state

### Energy is released as photos

23

## How can you find wavelength of light released during electron relaxation

###
Find photon energy given by the energy difference between energy levels

E = hc/λ

24

## What happens to a sound spectrum when the volume is lowered

### Peak frequencies stay the same but the amplitude/PD is lowered

25

## Explain the term poly crystalline in terms of the structure of metals

### Many small crystals whose close packed planes have different alignments or grain boundaries

26

## Why are steel alloys less ductile then pure iron

### Impurities pin dislocations so slip is more difficult

27

## How can conductivity of semi conductors be varied in the manufacturing process

### By adding impurities (doping) with more or less bonded electrons

28

## How can resolution be calculated

### change in x = Change in V/Sensitivity

29

## What is the Mean free Path of a particle in a gas

### The average distance traveled between consecutive collisions

30

## How can displacement of a gas particle be calculated

### Displacement = Mean Free path * (No.Collisions)^0.5

31

## How can number of collisions of a particle in a gas be calculated

### No. Collisions = Distance Travelled/Mean Free Path

32

## What happens to a beam of light as it moves from a higher to a lower refractive index

### Bends away from the normal

33

## How can you find the displacement of a bouncing object from a time-velocity graph

### Find the area for only the most recent bounce, as its displacement not distance travelled

34

## What is image, object, and focal length

###
The distance between the object and the centre of the lens is called the object distance, u

The distance between the centre of the lens and the image is called the image distance, v

The distance between the principle focus and the centre of the lens is called the focal length, f

35

## how can you work out the power required for a lens, so a short sighted person can see a closer then usual

###
Find the maximum curvature they can see

Find the curvature required to see

Curvature Required = max normal - required

36

## What would be useful properties of metal cable for a lift, and what properties of its micro structure allow for this

###
Strong, Stiff, High YM, Little Extension

Due to strong bonds and pinned dislocations allowing for no slip

37

## What would be useful properties of metal body panels for a crumple zone, and what properties of its micro structure allow for this

### A high breaking stress, high energy per unit volume, so absorbs more energy

38

## Imagine a Potential Dividing Circuit with an LDR and a Fixed Resistor. The user wants voltage to increase as light intensity increases. Where should the Voltmeter be put and why

###
As Light intensity increases the resistance decreases.

Therefore as light increases the resistance ration between the LDR and fixed resistor changes, with the fixed restore having a greater share of total resistance.

As Vout = Vcomp/Rtotal * Vin

The fixed resistor will get more and more PD so the volt meter should surround it

39

## What is meant by the term sensitivity of a sensing circuit

### Change in Output/Change In Input

40

## How can you find energy per unit volume from a stress strain graph

### Area underneath

41

## How can you release boding energy

### Fission of Fusion

42

## On an iterative formula what is the assumption and how can the model be improved

### Assumption is variable is constant during t, and it can be improved by reducing the change in time

43

## What is a 0 error

### Getting a Non-Zero reading when the reading should be 0

44

## How can you find the resistance of the component if given power and voltage

### P=v^2/r

45

## Whats peak to peak amplitude of a signal

### The difference between the highest and the lowest point on the signal

46

## Deduce an experiment to find the conductance of a material including how you would reduce uncertainty

###
Set up a circuit with a voltmeter, ammeter, cell, and the material

Measure voltage and current of the circuit, repeating and taking an average to reduce uncertainty and find range

G = 1/r

Measure the length and area of the component curing a Verner calliper

ϱ=GL/A

Make sure equipment is sensitive, an without zero errors

47

## What proves the idea of secondary wavelets during diffraction

### Single slit diffraction produces a circular spread

48

## How can you find current of 24 parallel cells if given internal resistance and EMF

### Current = Total EMF/Parallel Resistance

49

## In what direction does a wave vibrate if its been vertically polarised

###
It only vibrates vertically,

Note: Only if the wave is transverse

50

## What is v u and f of a lens

###
V is image distance

U is object distance

F is focal length

51

## Why can you assume f=v

### if u is very large 1/u is very small so 1/f roughly equals 1/v

52

## Why might a sensor have a slower reaction time

### Larger SA:V ratio, or covered in plastic

53