Calculating Relay Resistance for 12V Circuit

In summary, a relay in a circuit switches on when the current through the coil reaches 0.0048A. In this specific circuit, a 12V battery is connected in series with the relay and it switches on when a resistor of 800 Ohm is connected. Using the equation V=IR, the resistance of the relay can be calculated to be 1700 ohm. However, there may be a possibility that the circuit is not delivering the expected current of 0.0048A, leading to potential doubts about the simplicity of the question.
  • #1
Punch
44
0

Homework Statement



A relay switches on when the current through the coil reaches 0.0048A.

In a circuit, a battery of 12V is connected in series with this relay it switches on when another resistor of 800 Ohm is connected to it.

Calculate the resistance of the relay.

Homework Equations





The Attempt at a Solution



V= IR
12V = 0.0048A * (800 ohm + coil resistance)

12V / 0.0048A = 800 ohm + coil resistance

coil resistance = 2500 ohm - 800 ohm
=1700 ohm

However, I am not sure if I am on the right track...
 
Last edited:
Physics news on Phys.org
  • #2
Is the circuit with the battery and the resistor supposed to deliver 0.0048A? If so, your solution is right.
 
  • #3
ideasrule said:
Is the circuit with the battery and the resistor supposed to deliver 0.0048A? If so, your solution is right.

from the first line, "A relay switches on when the current through the coil reaches 0.0048A."

so can i conclude that the current passing through the coil has reached 0.0048A? which means that current in the circuit is 0.0048A

however, this question is worth 4 marks and it seems to easy for a usual 4 mark question...
 

Related to Calculating Relay Resistance for 12V Circuit

1. How do I calculate the resistance for a 12V circuit?

To calculate the resistance for a 12V circuit, you will need to use Ohm's Law, which states that resistance (R) is equal to voltage (V) divided by current (I). In this case, the voltage is 12V, so the formula would be R = 12V / I. You will need to know the value of the current in order to calculate the resistance.

2. What is the purpose of calculating relay resistance?

Calculating relay resistance allows you to determine the appropriate resistance value for a relay in a 12V circuit. This is important because using the wrong resistance could cause the relay to malfunction or fail, potentially damaging the circuit or the components within it.

3. How do I determine the current in a 12V circuit?

To determine the current in a 12V circuit, you will need to use a multimeter, which is a device that measures electrical current. Place the multimeter in series with the circuit, and the reading on the multimeter will indicate the current in amperes (A).

4. Can I use a lower or higher resistance for a relay in a 12V circuit?

No, it is important to use the correct resistance for a relay in a 12V circuit. Using a lower resistance could cause the relay to draw too much current and overheat, while using a higher resistance could prevent the relay from functioning properly.

5. Are there any other factors to consider when calculating relay resistance for a 12V circuit?

Yes, in addition to the voltage and current, you may also need to consider the power rating of the relay and the maximum current it can handle. It is important to choose a relay with a suitable power rating and ensure that the resistance value is within the recommended range for the relay.

Similar threads

Need help with a question on potential difference
    • Introductory Physics Homework Help
Replies
7
Views
621
Ohm's Law - Finding Source Voltage
    • Introductory Physics Homework Help
Replies
3
Views
622
Why do the headlights on the car become dim when the car is starting?
    • Introductory Physics Homework Help
Replies
4
Views
355
How can I calculate the equivalent resistance of this circuit?
    • Introductory Physics Homework Help
Replies
9
Views
1K
Total equivalent resistance of a combined circuit
    • Introductory Physics Homework Help
Replies
7
Views
1K
Understanding example in Wikipedia entry for open circuit voltage
    • Introductory Physics Homework Help
Replies
3
Views
629
How to solve for EMF and internal resistance in a circuit?
    • Introductory Physics Homework Help
Replies
8
Views
2K
The equivalent resistance for the resistors in this circuit?
    • Introductory Physics Homework Help
Replies
5
Views
1K
Coil Voltage/Current: Understand Resistance in Relay Circuits
    • Electrical Engineering
2
Replies
48
Views
4K
When a short-circuit exists, how to find the current?
    • Introductory Physics Homework Help
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top