A 30 Ω resistor has 6.0 V across it. Enter the current in A.
A 24 V battery drives a 5.0 Ω resistor and a 3.0 Ω resistor in series. One question asks for everything: the current, and the voltage across each resistor. You already own every tool this takes.
The job runs in three stages. Stage 1: find the total resistance, because series resistances add. Stage 2: find the current, using I = V/R with V the source voltage and R the total resistance. Stage 3: find each component's voltage, using V = IR with the one shared current.
A 24 V battery drives a 5.0 Ω resistor and a 3.0 Ω resistor in series. Find the circuit current and the voltage across each resistor.
Stage 1. Write down the values in the question:
V_source = 24 V; R₁ = 5.0 Ω; R₂ = 3.0 Ω; I = ?; V₁ = ?; V₂ = ?
Write down the equation for the total resistance:
R_total = R₁ + R₂
Substitute in the values, and calculate:
R_total = 5.0 + 3.0 = 8.0 Ω
Stage 2. Write down the equation for the current:
I = V/R, with V the source voltage and R the total resistance
Substitute in the values, and calculate:
I = 24/8.0 = 3.0 A
Stage 3. Write down the equation for each resistor's voltage:
V = IR
Substitute for the 5.0 Ω resistor:
V₁ = (3.0)(5.0) = 15 V
Substitute for the 3.0 Ω resistor:
V₂ = (3.0)(3.0) = 9.0 V
Check the answer:
15 + 9.0 = 24: the component voltages add up to the source voltage.
I = 3.0 A; the 5.0 Ω resistor has 15 V across it; the 3.0 Ω resistor has 9.0 V across it.
A 15 V battery drives a 4.0 Ω resistor and a 6.0 Ω resistor in series. Stage 1: what is the total resistance?
The same circuit: a 15 V battery driving 4.0 Ω and 6.0 Ω in series. Stage 2: what is the circuit current?
The same circuit: a 15 V battery driving 4.0 Ω and 6.0 Ω in series. Stage 3: what is the voltage across the 6.0 Ω resistor?
In the same circuit, the 3.0 Ω resistor is swapped for a 7.0 Ω resistor. Find the new current and both resistor voltages.
Stage 1. Write down the values in the question:
V_source = 24 V; R₁ = 5.0 Ω; R₂ = 7.0 Ω; I = ?; V₁ = ?; V₂ = ?
Write down the equation for the total resistance:
R_total = R₁ + R₂
Substitute in the values, and calculate:
R_total = 5.0 + 7.0 = 12 Ω
Stage 2. Write down the equation for the current:
I = V/R
Substitute in the values, and calculate:
I = 24/12 = 2.0 A
Stage 3. Write down the equation for each resistor's voltage:
V = IR
Substitute for the 5.0 Ω resistor:
V₁ = (2.0)(5.0) = 10 V
Substitute for the 7.0 Ω resistor:
V₂ = (2.0)(7.0) = 14 V
Check the answer:
10 + 14 = 24: the component voltages add up to the source voltage.
I = 2.0 A; the 5.0 Ω resistor has 10 V across it; the 7.0 Ω resistor has 14 V across it.
An 18 V battery drives a 5.0 Ω resistor and a 4.0 Ω resistor in series. What is the circuit current?
A 28 V battery drives an 8.0 Ω resistor and a 6.0 Ω resistor in series. What is the voltage across the 8.0 Ω resistor?
A heater element of 7.5 Ω and a resistor of 2.5 Ω run in series from a 30 V supply. What is the voltage across the heater element?