Calculate the maximum current a 140 ohms, 1/2 watt

In summary, to calculate the maximum current for a 140 ohm, 1/2 watt resistor, you can use Ohm's Law and plug in the voltage of 0.5 volts to get a current of 0.00357 amps or 3.57 milliamps. It is important to calculate the maximum current for a resistor to ensure it can handle the current without overheating or becoming damaged. Factors that can affect the maximum current include resistance value, power rating, temperature, and material. To increase the maximum current, you can decrease resistance or increase power rating, but it is best to consult a datasheet or seek professional advice. Exceeding the maximum current can result in overheating and potential damage to the
  • #1
Bobzombie
2
0
I have looked thought all my notes and books and can not find the formal on how to do this question. I'm slowly going out of my mind any help would be great

Calculate the maximum current a 140 ohms, 1/2 watt resistor can have flowing through it safely.
Enter answer: mA

Then the 2nd part of the question is

What is the maximum e.m.f. which may be applied to the resistor above without causing overheating?

Enter Part 2 answer: V
 
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  • #2
Don't you have some fundamental equations that relate voltage (V), resistance (R), current (I), and power (W)? You'll need them.
 
  • #3


To calculate the maximum current that can flow through a resistor, we can use Ohm's law, which states that current (I) is equal to voltage (V) divided by resistance (R). In this case, the resistance is 140 ohms and the power is 1/2 watt. To calculate the maximum current, we need to first convert watts to volts using the formula P=IV. So, 1/2 watt can be written as 1/2 volt-amp. Now, we can plug in the values into Ohm's law: I = (1/2 volt-amp) / 140 ohms. This gives us a maximum current of 0.00357 amps, or 3.57 milliamps (mA).

To answer the second part of the question, we need to use the formula P=IV again, but this time, we are solving for voltage. Since the power is 1/2 watt and the current is 0.00357 amps, we can write the equation as 1/2 = (0.00357)V. Solving for V, we get a maximum voltage of 140 volts. This means that we can safely apply a maximum of 140 volts to the resistor without causing it to overheat.
 

1. How do I calculate the maximum current for a 140 ohm, 1/2 watt resistor?

The maximum current for a resistor can be calculated using Ohm's Law, which states that current (I) is equal to the voltage (V) divided by the resistance (R). In this case, the voltage is given as 1/2 watt, which is equivalent to 0.5 volts. Plugging this into the formula, we get:
I = 0.5V / 140 ohms = 0.00357 amps or 3.57 milliamps.

2. Why is it important to calculate the maximum current for a resistor?

Calculating the maximum current for a resistor is important because it allows us to determine if the resistor can handle the amount of current passing through it without overheating or becoming damaged. It also helps us to choose the appropriate resistor for a specific circuit or application.

3. What factors can affect the maximum current for a resistor?

The maximum current for a resistor can be affected by its resistance value, power rating, temperature, and the type of material it is made of. Higher resistance values and power ratings can handle more current, while higher temperatures can decrease the maximum current limit. Additionally, different materials have different temperature coefficients that can impact the maximum current.

4. How can I increase the maximum current for a resistor?

To increase the maximum current for a resistor, you can either decrease its resistance or increase its power rating. However, it is important to note that these changes may also affect other aspects of the resistor's performance, so it is best to consult a datasheet or seek professional advice before making any modifications.

5. What happens if the maximum current for a resistor is exceeded?

If the maximum current for a resistor is exceeded, it can overheat and potentially cause damage to the resistor or other components in the circuit. This can result in a decrease in the resistor's resistance value, which can affect the overall performance of the circuit. It is important to always stay within the maximum current limit to ensure the safety and functionality of the circuit.

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