Qualification > Sciences
physics help !!
QuickSilver:
--- Quote from: nid404 on June 09, 2009, 09:23:19 am ---
--- Quote from: astarmathsandphysics on June 09, 2009, 09:18:31 am ---
--- Quote from: nid404 on June 09, 2009, 09:10:44 am ---but astar how is the pd decreasing, cuz the current is increasing( resistance is reduced.) And when the current increases rotation in a motor is faster no?? Plz explain astar...i too am giving my exam tomorrow
--- End quote ---
The voltage a cross the motor is the voltage across that part of the resistor between X and th other wire connecting the motor to the circuit. If you move the conact at x to the bottom of the resistor this voltage will be zero and the current and voltage and resistance in the circuit is irrelevant. Hence the motor stops
--- End quote ---
yeah thanks sir, i understand too :)
ok so when V is 0, rest pf the things are not to be considered..so now i understand that the resistor is acting like a potential divider.
thanks sir
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astarmathsandphysics:
--- Quote from: QuickSilver on June 09, 2009, 09:20:22 am ---
--- Quote from: astarmathsandphysics on June 09, 2009, 09:18:31 am ---
--- Quote from: nid404 on June 09, 2009, 09:10:44 am ---but astar how is the pd decreasing, cuz the current is increasing( resistance is reduced.) And when the current increases rotation in a motor is faster no?? Plz explain astar...i too am giving my exam tomorrow
--- End quote ---
The voltage a cross the motor is the voltage across that part of the resistor between X and th other wire connecting the motor to the circuit. If you move the conact at x to the bottom of the resistor this voltage will be zero and the current and voltage and resistance in the circuit is irrelevant. Hence the motor stops
--- End quote ---
ohh so ok V and I are inversely proporional but when V=0 (zero), then no current can occur right??
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No Vmotor=(Vsupply*Rout/(Rout+R) where R is the other resistance in the cicuit
astarmathsandphysics:
Yes it is a potential divider
Kim:
hey Astar cud u help with nov 2006 p1 q3?plz it will be really appreciated
nid404:
--- Quote from: kim on June 09, 2009, 09:37:13 am ---hey Astar cud u help with nov 2006 p1 q3?plz it will be really appreciated
--- End quote ---
60km/h
30km in 1/2 hour..so in 1 hour it will be 60
ans is D
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