Electrical circuit
Transcript of Electrical circuit
Potential differentPotential different is difined as electric work/energy needed to flow the positive electric charge to another point.
+QW
•A
•B
High potentialVA
Low potentialVB
Q
WVor
Q
WV
V = potential different ( J/C = volt = V )W = electric work/energy ( J = joule)Q = electric charge ( C = coulomb )
BA VVVV
TASK1. Electrical energy of 90 joules used to transfer 30 coulombs of electric
charge from point A to point B. If the electric potential point A is 12 volts, what is the electric potential point B?
2. Electrical charges 40 C move from point X to point Y need electrical energy of 120 joules. If the electric potential point Y is 6 volts, what is the electric potential point X?
Electrical measuring instruments
1. The Voltmeterto measure the electrical potential difference or voltage.
Symbol:
The Voltmeter installation: Parallel
How to read ammeter and voltmeterThe maximum scale
Appointed scale needle
Measuring limit
Measuring results =Appointed scale needle
The maximum scalex Measuring limit 34
100X 1A = 0.34 A=
The maximum scaleAppointed scale needle
Measuring limit
Measuring results =Appointed scale needle
The maximum scalex Measuring limit 40
100X 5V = 2 V=
Ohm's Law
S
If the switch S is closed then the electrical current flowing in the circuit.
According to Ohm:electrical current is proportional to the potential different and inversely proportional to the resistance.
Formula
R
VI or RIV .
V = potential different ( volt = V)I = intensity of current / current ( ampere = A)R = resistance ( ohm = Ω )
R
VI
Relationships between variables in Ohm's law.
or RIV .
1) An electric current is proportional to the potential different.
2
1
2
1
V
V
I
I
I1 = initial electric current. ( A, mA)I2 = final electrical current. (A, mA)V1 = initial potential different (volt = V )V2 = final potential different ( volt = V )
V-I graph or I-V graph
V (potential different)
I (electric current) V (potential different)
I (electric current)
or
2) Electric current is inversely proportional to resistance.
1
2
2
1
R
R
I
I
I1 = initial electric current. ( A, mA)I2 = final electrical current. (A, mA)R1 = initial resistance ( ohm = Ω )R2 = final resistance ( ohm = Ω )
R-I graph or I-R graph
I (electric current)
R (resistance) I (electric current)
R (resistance)
or