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Posted

Hi,
        I have one question. Suppose I have 24v/2a DC power supply. If I connect 8 ohm resistor across this power supply what will be the current flowing through the resistor? And on what factors does the maximum current of power supply depend?


Posted

1) Use Ohm's law.

2) If the load tries to draw too much current, the power supply will do one of the following:

  • Overheat if the load is left connected for too long and catch fire if there's no protective thermal fuse.
  • Overheat, then shut down and not turn back on again until either the power supply or load is disconnected.
  • Blow a fuse or trip a breaker which will need replacing or resetting.
  • The power supply could reduce the voltage until only 2A flows.


Posted

Thanks Hero999 for your quick reply. Of the following four options what will you choose?

1) 0.5A
2) 1.0A
3) 2.0A
4) 3.0A

I was asked this question during placement exam and I marked 2A giving the explanation that voltage will drop until the value of current is reduced to 2A. Am I correct? 

Thanks again.

Posted

I wouldn't choose either option without more information about the power supply.

If it was an exam, I'd calculate the expected current using Ohm's law and put a comment on the paper saying that it exceeds the capacity of the power supply which will fail or protect itself depending on the design.

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