Find the resistance of a circuit runs with 190 µA and 122 nV Note: pls refer to the given lesson. Follow the proper formula
Find the resistance of a circuit runs with 190 µA and 122 nV Note: pls refer to the given lesson. Follow the proper formula
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Find the resistance of a circuit runs with 190 µA and 122 nV
Note: pls refer to the given lesson. Follow the proper formula
Transcribed Image Text:Ohm's Law
The relationship among voltage, current, and resistance is summarized by a
statement called Ohm's law. George Simon Ohm discovered that the current in a
circuit is directly proportional to the voltage established across the circuit and is inversely
proportional to the resistance of the circuit. In short,
Current (1)
= Voltage (V)
Resistance (R)
Or in units form: Amperes (A)= Volts (V)
Ohms
Current and voltage are proportional to each other for a given circuit of a constant
resistance .It tells us that, to obtain twice as much of the original current, we must
double its voltage. Increase in voltage means increase in current. On the other hand, if
you double the resistance, the current will be half what it would be otherwise. The
greater the resistance, the smaller the current. The lesser the resistance, the greater the
current.
Ohm's law states that 1 A is produced by 1 V of potential difference across a
circuit that has 10 resistance.
Example 1
Find the current I through a resistor of resistance R = 2 2 if the voltage across the
resistor is 6 V.
Given:
R= 20
V = 6 V
Find I
Solution:
I= V/R
1 = 6V
202
1 = 3A
KEEP IN MIND!
For a given potential difference,
more resistance means less current.
7
Transcribed Image Text:Resistivity
Most of the times, lighting a bulb is quite impossible without the use of a wire for it
will be a network of the charges flowing to bring current. Conducting materials are used
differently. Flat irons, for example, use copper wire to connect to a voltage source and
nichrome wire to heat the appliance. We can use the resistivity to identify an unknown
material since resistivity is unique to every kind conducting material.
Resistivity measures how strong a material opposes the flow of electric current.
Resistivity, commonly symbolized by the Greek letter rho, p, is quantitatively equal to
the resistance R of a wire, multiplied by its cross-sectional area A, and divided by its
length I;
In short;
In units;
You can refer to the tables below
Resistivity of conducting materi-
als
Material
Aluminum
Copper
Gold
Iron
Silver
Tungsten
Nichrome
Carbon
20995
AMERICAN STANDARD
WIRE GAUGE
Resistivity
Qm
2.8 x 10-8
1.7 x 10.8
2.4 x 108
9.7 x 10-8
1.6 x 10-8
5.6 x 10-8
1.5 x 10-6
3.5 x 10-5
źr
urements of wire gauge.
Table 1:Resistivity of conducting materials in 2m.
p = RA/I
p = Qm²/m
p = Qm
for the resistivity of conducting materials and
equiv-
alent
meas-
American
Wire
Gauge
(#AWG)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Cross
Diameter Diameter Sectional
Area
(mm²)
42.4
(inches) (mm)
0.289
7.35
0.258
6.54
0.229
5.83
0.204
5.19
0.182
4.62
0.162
4.11
0.144
3.67
0.129
3.26
0.114
2.91
0.102
2.59
0.0907
0.0808
0.072
0.0641
0.0571
▬▬▬▬▬▬▬
0.0508
0.0453
0.0403
0.0359
0.032
0.0285
0.0254
0.0226
0.0201
0.0179
0.0159
2.3
2.05
1.83
1.63
1.45
1.29
1.15
1.02
0.91
0.81
0.72
0.65
0.57
0.51
0.45
0.4
33.6
26.7
21.1
16.8
13.3
10.6
8.36
6.63
5.26
4.17
3.31
2.63
2.08
1.65
1.31
1.04
0.82
0.65
0.52
0.41
0.33
0.26
0.2
0.16
0.13
Cross
Sectional
Area
(m²)
4.24x10-5
3.36x10-5
2.67x10-5
2.11x10-5
1.68x10-5
1.33x105
1.06x10-5
8.36x10€
6.63x10€
5.26x10€
4.17x10
3.31x10
2.63x10€
2.08x10€
1.65x10
1.31x10
1.04x10€
8.20x107
6.50x10
5.20x107
4.10x10-7
3.30x107
2.60x107
2.00x107
1.60x107
1.30x10
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