Lab Notes: Week 3, Meter and Ohm's Law, Physics 3LB at UCI

Week 3: Meter and Ohm's Law
Monday, January 20, 2020 2:49 PM


Va

• Ohm's Law: voltage V is linearly proportionate to the current that flows thru the


material. (V = IR)
Vb

• Circuits contain more than one resistor: either connected in parallel or in series.


○ Resistors used to either INC or DEC the amount of current that flows thru the


circuit.


○ Parallel resistors allow more current to flow thru the circuit. (Ieq =


I1+I2+I3+…)


○ Series resistors allows less current to flow thru b/c the current path now


passes 2 resistors.


• Voltmeter: measures voltage by measuring the small amount of current that flows


thru the internal resistor.


○ Ri : internal resistance of the voltmeter. (For reading to be accurate)Ideally

IDEALS for meters.
much larger than R (Ri > R1).



○ Voltmeter is placed in parallel w/ the resistor. -> Ri and R are connected in



parallel circuits.


• Ammeter: measures current by detecting the voltage that appears across the


internal resistor of the ammeter. Just a wire…