Jayce
Newbie level 5
Problem : A 33 Ω half-watt resistor and a 330 Ω half-watt resistor are connected across a 12 V source. Which one(s) will overheat?
Choices: A.) 33 Ω B.) 330 Ω C.) Neither resistors D.) Both will overheat.
My solution: Since the phrase is "the resistors are connected across the voltage source, I assumed that the resistors are in parallel. So, same voltage. V = 12V
Power dissipated in 33 Ω = V^2 / R1 = 12^2 / 33 = 4.36 W
Power dissipated in 330 Ω = V^2 / R2 = 12^2 / 330 = 0.436 W
The rating of the 33 Ω resistor is half-watt and the power dissipated in it is 4.36 which is more than the rating. Hence, 33 Ω resistor will overheat.
BUT the answer on the book is neither resistor will overheat. There is no solution. Now I am confused which is the correct answer as others say the answer should be (A) which is 33 Ω, saying that the resistors is connected in series and not int parallel.
Or maybe, it's because of the half-watt rating in both of the resistors. It is designed to keep the heat at half-watt, avoiding both to overheat... not sure.
What do you think guys?
Choices: A.) 33 Ω B.) 330 Ω C.) Neither resistors D.) Both will overheat.
My solution: Since the phrase is "the resistors are connected across the voltage source, I assumed that the resistors are in parallel. So, same voltage. V = 12V
Power dissipated in 33 Ω = V^2 / R1 = 12^2 / 33 = 4.36 W
Power dissipated in 330 Ω = V^2 / R2 = 12^2 / 330 = 0.436 W
The rating of the 33 Ω resistor is half-watt and the power dissipated in it is 4.36 which is more than the rating. Hence, 33 Ω resistor will overheat.
BUT the answer on the book is neither resistor will overheat. There is no solution. Now I am confused which is the correct answer as others say the answer should be (A) which is 33 Ω, saying that the resistors is connected in series and not int parallel.
Or maybe, it's because of the half-watt rating in both of the resistors. It is designed to keep the heat at half-watt, avoiding both to overheat... not sure.
What do you think guys?