P4 Flashcards
what happens when you rub a polystyrene rod with a dry cloth?
-transfers, electrons to the surface atoms of the rod from the cloth
-The rod becomes negative charged and the cloth becomes positivly charged
what happens when you rub a perspex rod with a dry cloth?
-transfers electrons from the surface atoms of the rod onto the cloth
-The perspex rod becomes positively charged and the cloth becomes negatively charged
what does Q = IT represent?
Q= charge flow
I=current
T=time
what happens to A thermistors resistance as temperature increases?
decreases
what happens to an LDR‘s resistance when light intensity increases?
decreases
what does a resistor graph look like?
straight through origin
this is because of ohms law that states:
-The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor
what does a filament lamp graph look like?
-A stretched out S
-The resistance of a filament lamp increases as the filamebt temperature increases
-The atoms in the metal filament vibrate more as the temperature increases so they resist the passage of the electrons through the filament more
what does a diode graph look like?
-A flatline with a diagonal L
-There is a flat line because the Diode current only flows in one direction
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how is the potential difference shared in a series circuit
-The total potential difference of the power supply is shared between the components
how do you find the total resistance in a series circuit?
-Rtotal = R1+R2
how do you find the total sum of current in a parallel circuit?
-It’s the sum of the currents through the separate components
how do you find the sum of the potential difference in a parallel circuit?
-it’s the same across all components
what is resistance measured in?
Ohms
what is resistance?
the restricted flow of electrons
what is potential dofferbve
it is measured energy between two points
what happens when you add more resistors in a parallel circuit?
The resistance decreases
why does static shocks occur?
-static shocks occur when electrons transferred to us after being rubbed onto us
-they then want to transfer to the ground
-this happens when electrons get passed on when we touch an insulator and travel to the Earth
