What oxygen containing compounds are added to petrols to increase the octane number?
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Oxygen and Octane Number
oxygen molecules have a high octane number
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Why do alcohols burn more completely?
-needs less O2 -for same amount of fuel
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Least Penetrating Radiation
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Most Deflected Radiation
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Why do metals conduct electricity?
free delocalised electrons carry a charge through the cations
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Amylose Structure
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Amylopectin Structure
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Starch Molecules
amylose + amylopectin
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Oxygen and Permeability
-small atom -non polar -able to diffuse
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Chlorine ion and Permeability
-they have a charge - cant pass through a pholip bl -requires channel proteins -active transport -CTFR channel protein
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Water and Permeability
-passes through epithelial cells -polar so it struggles -it is small so it does manage -uses channel proteins as well
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Blood Clot Process
-cascade -thromboplastin is an enzyme -prothrombrin>thrombrin -fibrinogen>fibrin -insoluble fibrin mesh traps platelets/RBC -calcium/potassium facilitate enzymes
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What is the population not?
all the people being tested
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write the equation
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High Resistance Anomaly
a resistance reading which is significantly higher than others in the survey
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Less water and Resistivity
less resistivity
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If there are 2 wires and resistivity is being measured
times the length by 2
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Error Equation
the added value/original value x 100
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When writing about how significant something is
write how and also compare it to other values that have been measured and wh
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Potential Divider
two resistors connected in series with a supply. Usually represented as one box and the p.d. is shared equally between them
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How can Potential Dividers be used in circuit?
to supple p.d. to another circuit that ha less than the p.d. of the power supply
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In conventional current the current leaves the +/- side?
it leaves the positive side
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What happens to the voltage as it leaves a resistor
the voltage becomes 0
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How do you decrease the voltage in a resistor
you decrease the distance travelled
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Why wouldn't a bulb light if it was over a 3.0v potential divider?
-lamp is parallel with lowest of 1/3 of AB -when resistors are in parallel the resistance decreases -p.d. across a lamp reduced to below 3v -no longer enough current to light the lamp
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What does the way an electron travels around an object tell you about the object?
the material has a regular structure
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The spacing of the objects atoms are the same as?
the electrons wave length
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Why should the resistance of a resistor should not be measured in a circuit?
-other currents/voltages/resistances are present -example (wires) -change in current changes resistance readings
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Open Circuit
the power supply has no connections between terminals and have a high resistance I=0 V=
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Short Circuit
power supply terminals are joined by a connection with no resistance V=0 I=
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Conventional is positive which means
current leaves the positive terminal and enters the negative
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Current in a Metal
the current is negative electrons and so they move in the opposite direction
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measures current (amps) and is connected in series
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measures potential difference (volts) and is connected in parallel
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Increased Potential Difference on Current
increase in curren
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Ohms Law
current is directly proportional to potential difference
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Non Ohmic
not proportional
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Increases Current on Resitance
decrease in resistance
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Why does resistance increases in metals?
-free electrons -as they collide with lattice vibrations they scatter -hotter metal more vibrations -more collisions between atoms and electrons -the current decreases -if the current has decreased then the resistance has increases
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The faster electrons move
the slower the current
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have fewer free electrons
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Positive Semi Conductor
resistance increases as the temperature increases
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Negative Semi Conductor
resistance decreases as the temperature decreases
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A material with a small resistivity?
it will be a good conductor as it has a large number of free electrons
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If the device obeys Ohm's Law
the resistance will no change
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Resistance base unit
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Resistance SI unit
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Resistance equation symbol
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Power definition
the rate of doing work and the transfer of energy
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Power base unit
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Power SI unit
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Power equation symbol
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Power equation
W/t E/t VQ/t
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Current definition
rate of flow of charged particles
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Current base unit
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Current SI unit
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Current equation eymbol
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Potential Difference definition
measure of energy transfer between two points
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Potential Difference base unit
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Potential Difference SI unit
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Potential Difference equation symbol
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Potential Difference equation
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Charge base unit
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Charge SI unit
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Charge symbol equation
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Charge equation
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Work definition
energy transferred
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Work base unit
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Work SI unit
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Work equation symbol
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Work equation
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Resistance equation
VI pl/A
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Current equation
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Electro Motive Force definition
energy supplied to each coulomb
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Electro Motive Force equation
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Electro Motive Force equation meanings
V= energy transferred by load resistor Ir= energy transferred due to internal heating
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Extra Symbols (n,q,v)
n= the number of conduction/free electrons per unit volume q=the charge on an electron v= the drift velocity of a free electron
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Area under a velocity time graph
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Ductile is also
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How to find upthrust
times the mass of the water displaced by gravity
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Stokes Law is used to find
viscous drag
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Rate of Work Done
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The maximum speed equation
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When calculating from a graph
use the end
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Energy stored in a material on a graph
area under the graph = 1/2F x
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Other cards in this set

Card 2


Oxygen and Octane Number


oxygen molecules have a high octane number

Card 3


Why do alcohols burn more completely?


Preview of the front of card 3

Card 4


Least Penetrating Radiation


Preview of the front of card 4

Card 5


Most Deflected Radiation


Preview of the front of card 5
View more cards


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