Post on 03-Jan-2016
Ohm’s Law
Conductor•A conductor is a material that current can pass through easily, like metals.
Insulator•An insulator is a material that current cannot pass through easily, like plastic.
Resistor•A resistor is a material that resists, but doesn’t stop the flow of current.
ResistanceOpposition to the flow of electrons.
It changes electrical energy into thermal energy and/or light.
Measured in ohms. Conductors have less resistance than insulators.
Wire resistance greater for:
1) Longer wires
2) Thinner wires
3) Higher temperatures
Electrical Resistance.– This is when current flow is slowed down.– Current seems to lose energy. Actually, the electrical
energy is converted into heat and/or light.– The symbol is R.– The unit is the ohm ().
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Flowing charge is called current. The symbol is I and the unit is the ampere or amp (A).
SIM
For your notes: Electric Current
1. The reason electric charge flows from one place to another is voltage. a. Voltage is the difference in electrical potential between two places where electrons are flowing.
b. Voltage is the “push” that makes electric charges move.
c. Measured in volts (V).
2. The flow of electric charge is called current.
a. Current is measured in amperes, or amps (A).
b. Voltage causes current.
3. The amount of electric charge is measured in coulombs.
a. 1 coulomb is the charge carried by 6.24 x 10^18 electrons.
b. 1 amp is 1 coulomb per sec.
6. Ohm’s law
Voltage = Current * Resistance V = I * R
I
V
R
Connecting Ohm’s Law to Water
How would turning the speed of a water hose up (more voltage) affect the current (amount of water flowing out of the tube)?
V = I * R
Connecting Ohm’s Law to Water
If resistance on a water hose goes up (you clamped the tube) how would the current change if you kept the hose on the same speed or with the same force (voltage was the same)? V = I * R
Connecting Ohm’s Law to Water
Suppose you clamped the tube (increased the resistance) AND you wanted more water to come out of the tube (increase current), what would you need to do to the voltage (the flow of the water)?
V = I * R