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Flashcards in Physics In Action Deck (53):

Define Ionisation

When particles loose some electrons to become positively charged ions


How can you find resistance from a voltage current graph

The gradient if its a straight line through the origin

V=IR if not


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


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


What is plastic behaviour

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


What is machinability

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


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


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


where λ is wavelength
n is the order of maxima
Θ is the angle of the maxima


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


Define Brittle

The tendency for a material to fracture under a force


Define Ductile

The ability for a material to be drawn or stretched


Define Hardness

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


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


How can the magnification of an image be calculated

M = v/u


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

Image Size = Object Size * Magnification


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


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


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


Define Strong

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


How can you find a signals resolution

Resolution = P.D Range/No. Levels


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


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

Energy is released as photos


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


What happens to a sound spectrum when the volume is lowered

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


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


Why are steel alloys less ductile then pure iron

Impurities pin dislocations so slip is more difficult


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

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


How can resolution be calculated

change in x = Change in V/Sensitivity


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

The average distance traveled between consecutive collisions


How can displacement of a gas particle be calculated

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


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

No. Collisions = Distance Travelled/Mean Free Path


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

Bends away from the normal


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


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


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


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


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


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


What is meant by the term sensitivity of a sensing circuit

Change in Output/Change In Input


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

Area underneath


How can you release boding energy

Fission of Fusion


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


What is a 0 error

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


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



Whats peak to peak amplitude of a signal

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


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


Make sure equipment is sensitive, an without zero errors


What proves the idea of secondary wavelets during diffraction

Single slit diffraction produces a circular spread


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

Current = Total EMF/Parallel Resistance


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

It only vibrates vertically,

Note: Only if the wave is transverse


What is v u and f of a lens

V is image distance
U is object distance
F is focal length


Why can you assume f=v

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


Why might a sensor have a slower reaction time

Larger SA:V ratio, or covered in plastic


What makes GRP more useful then glass or epoxy resin

Expect resin binds to glass mat, transferring stress to stiffer glass fibbers, but its flexibility stops cracks from propagating through the material