Ohm’s Law and Circuit Basics Venus Is Round Ohm’s Law and Circuit Basics

Current in Circuits Ohm’s Law CURRENT is a REACTION to the ACTION of VOLTAGE How much current depends on: VOLTAGE  MORE voltage = MORE current RESISTANCE  MORE resistance = LESS current Ohm’s Law

Example #1 The voltage supplied to a circuit with a resistance of 100 ohms is 25 volts. How much current will flow in this circuit? I = V / R I = 25 V / 100 Ω I = 0.25 A

Example #2 A current of 2.0 amperes flows through a circuit with a resistance of 10 ohms. What is the voltage supplied to the circuit? I = V / R 2A = V / 10Ω V = 20V

Example #3 A 10 volt battery is connected to a circuit, allowing 5 amperes of current flow. Calculate the resistance of the circuit. I = V / R 5A = 10V / R R = 2Ω

Circuit A path through which current flows from an area of high voltage to an area of low voltage.

Circuit Elements Other Elements Resistances Measurement Devices Voltage sources Fixed resistor – resistance does NOT change once installed Opens and closes the circuit turning current flow on or off Resistance CAN be changed after installation Voltmeter is a device for measuring VOLTAGE How hard are electrons being pushed? Ammeter is a device for measuring CURRENT How many electrons flow per second? Provide electrical potential for electrons – “PUSHING” or “PUMPING” them through the circuit Special resistor – used to produce light!

Measurements V V V A A V 100V R = 10Ω 10A 10A 0V 0V Voltmeter measures RELATIVE differences from OUTSIDE the circuit Ammeter measures flow INSIDE the circuit V = 100V V 100V