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…
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…
