Resistor circuit, potential drop and time

In summary: PS and OHMS give you VOLTS for the power equation. So you don't need anything else.In summary, the problem involves a 200 volts battery connected to three resistors, with a 32 ohm resistor in the circuit. To find the potential drop across the 32 ohm resistor, the parallel resistor circuit between the 10 and 40 ohm resistors is first found, resulting in a single resistor of 8 ohms. By using V=IR, the current flowing through the 32 ohm resistor can be determined, and then used to calculate the voltage across the resistor. Part b of the problem involves determining the amount of current needed for a 10 ohm resistor to raise the temperature of 60
  • #1
scholio
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0

Homework Statement



a 200 volts battery is connected to three resistors as shown, see attachment.

a) what is the potential drop across the 32 ohm resistor?

b) the 10 ohm resistor is immersed in 60 grams of water at 20 deg celsius. how long much current flow for the water to reach 40deg celsius. assume that there is not heat loss from the water through the walls of the container.

Homework Equations



parallel resistors 1/R = 1/R_1 + 1/R_2

series resistors R = R_1 + R_2

potential V = IR where I is current, R is resistance

QV/t = I^2R where Q is charge, t is time

The Attempt at a Solution



part a. first i found the parallel resistor circuit between the 10 and 40 ohm resistor, getting 8 ohms,

then i connected the new 8ohm resistor to the 32 ohm and got a single resistor of 40 ohms.

i tried using V =IR to solve for potential, but it didn't work

QV/t = I^2R , couldn't use that and solve for V because i didn't have time

does the problem involve a temperature coefficient of resistivity of water to solve for part b?

any help, for either part, appreciated
 

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  • #2
scholio said:
part a. first i found the parallel resistor circuit between the 10 and 40 ohm resistor, getting 8 ohms,
Correct.

then i connected the new 8ohm resistor to the 32 ohm and got a single resistor of 40 ohms.

i tried using V =IR to solve for potential, but it didn't work
You first have to determine the current. What is the current flowing through the 32 ohm resisitor (hint: it is a function of the total voltage and total resistance)? Then use V=IR to determine the voltage across the 32 ohm resistor.

QV/t = I^2R , couldn't use that and solve for V because i didn't have time

does the problem involve a temperature coefficient of resistivity of water to solve for part b?

any help, for either part, appreciated
Why use QV/t for power? Q/t = current = I so:

[tex]P = VI = I^2R[/tex]

AM
 
  • #3




I would like to clarify a few things before providing a response to the given content. Firstly, the attachment mentioned in the homework statement is missing, so I am not able to see the circuit and the values of the resistors. Secondly, the equations mentioned in the homework statement are not relevant to the given problem. The parallel and series resistor equations are used to calculate the equivalent resistance of a circuit, and the potential and current equations are used to calculate the voltage and current in a circuit. Lastly, the temperature coefficient of resistivity of water is not mentioned in the problem, so it is not necessary to consider it in the solution.

Having said that, I will provide a general response to the given problem. To calculate the potential drop across the 32 ohm resistor, we need to know the current flowing through it. This can be calculated by using Ohm's law, V = IR, where V is the battery voltage and R is the equivalent resistance of the circuit. Once we have the current, we can use Ohm's law again to calculate the potential drop across the 32 ohm resistor.

For part b, we need to calculate the time required for the temperature of the water to increase from 20 degrees Celsius to 40 degrees Celsius. This can be done by using the equation Q = mcΔT, where Q is the heat energy required, m is the mass of the water, c is the specific heat capacity of water, and ΔT is the change in temperature. Once we have the heat energy, we can use the equation Q = I^2Rt, where I is the current flowing through the resistor, R is the resistance of the resistor (10 ohms in this case), and t is the time. By equating the two equations, we can solve for t and get the time required for the water to reach 40 degrees Celsius.

I hope this helps. It is important to note that the solution may vary depending on the specific values and circuit shown in the attachment. It is always best to provide all the necessary information and equations when asking for help with a problem.
 

1. What is a resistor circuit?

A resistor circuit is a combination of resistors connected in a circuit. Resistors are components that resist the flow of electric current and are commonly used to control the amount of current flowing through a circuit.

2. How does potential drop affect a resistor circuit?

Potential drop, also known as voltage drop, is the decrease in electric potential across a resistor. This decrease in potential is directly proportional to the resistance of the resistor. In a resistor circuit, potential drop can affect the amount of current flowing through the circuit, as well as the amount of heat generated by the resistors.

3. What is the relationship between resistance and time in a resistor circuit?

The relationship between resistance and time in a resistor circuit depends on the type of resistor being used. In general, as the resistance of a resistor increases, the time it takes for current to flow through the circuit also increases. This is because higher resistance slows down the flow of current through the circuit.

4. How does the number of resistors in a circuit affect the potential drop?

The number of resistors in a circuit can affect the potential drop in two ways. First, adding more resistors in series will increase the overall resistance of the circuit, resulting in a higher potential drop. Second, adding more resistors in parallel will decrease the overall resistance, resulting in a lower potential drop.

5. What factors can affect the time it takes for current to flow through a resistor circuit?

The time it takes for current to flow through a resistor circuit can be affected by several factors, including the resistance of the resistors, the voltage of the power source, and the type of material the resistors are made of. Other factors such as temperature and the length of the circuit can also have an impact on the time it takes for current to flow through the circuit.

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