Ohm's Law Summary
Generator
Materials:
ammeter
voltmeter
rheostat
connecting wires
generator
protective resistor
Current voltage Characteristic Curve
shape:
Equation : U= -rI + E
U being the voltage across generator
r being the internal resistor of generator ( r= -slope) unit is in (Ω)ohms
E is the electromotive force for the generator in V. it is maximum voltage for generator for I=0 A
I : The current passing through the generator in (A)
characteristics of Generator
r and E
Special Cases
ideal generator
No heat loss
r =0 so U generator = E (constant
short circuited generator
generator is short circuited
U generator = 0 so -rI +E = 0
I short circuit = E/r
Resistor
Current voltage Characteristic Curve
Equation : U = R × I
U being the voltage across ohmic conductor
R being the slope =Ua - Ub / Ia - Ib
I is the current passing through ohmic conductor in (A)
characteristics of Resistor is R
shape:
Equation : U rec = r’ I + E’
U being the voltage across generator
r being the internal resistor of the reciever ( r= -slope) unit is in (Ω)ohms
E is the electromotive force for the receiver in V. It is the minimum voltage needed by a receiver to start functioning
I : The current passing through the receiver in (A)
ammeter
voltmeter
connecting wires
Special Cases
ideal reciever
No heat loss
r =0 so U reciever = E (constant
short circuited reciever
receiver is short circuited
U rec = Uwire = 0 V
If a receiver is BLOCKED
It acts as a resistor of
resistance r’
E' = 0v so Urec=r'I
Materials:
ammeter
voltmeter
Switch
connecting wires
Resistor of unknown resistance (R)
Adjustable voltage source
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