Correct question: When two resistors are connected in parallel across a battery of unknown voltage, one resistor carries a current of 3.3 A while the second carries a current of 1.8 A .
What current will be supplied by the same battery if these two resistors are connected to it in series?
Answer:
1.164 A
Explanation:
From the question,
Let the unknown voltage of the batter = V.
Since the two resistors are connected in parallel,
The voltage across each of the resistor is the same = V,
Then,
From ohm's law,
V = IR................... Equation 1
Where V = Voltage, I = Current, R = Resistance.
make R the subject of the equation
R = V/I................ Equation 2
For the first resistor,
Given: I₁ = 3.3 A, V = V.
Substitute into equation 2
R₁ = V/3.3 Ω
For the second resistor,
Given: I₂ = 1.8 A
Substitute into equation 2
R₂ = V/1.8 Ω.
When the Resistors are connected in series,
Rt = R₁+R₂
Where Rt = Total resistance.
Rt = V/3.3+V/1.8
Rt = (1.8V+3.3V)/(3.3×1.8)
Rt = 5.1V/5.94
Rt = 0.859V.
Applying,
I' = V/Rt
where I' = current supplied by the battery, If the two resistors are connected in series
I' = V/0.859V
I' = 1.164 A
