The battery for a certain cell phone is rated at 3.70 V. Accordin...

Question

The battery for a certain cell phone is rated at 3.70 V. According to the manufacturer it can produce 3.15 * 10^4 J of electrical energy, enough for 5.25 h of operation, before needing to be recharged. Find the average current that this cell phone draws when turned on.

Accepted Answer

Hey everyone welcome back in this problem. We have a portable electric drill that uses an 18 volt battery. The battery stores 3.24 times 10 to the five jewels of electrical energy and can sustain the drill for 15 minutes for each full charge were asked to determine the average current supply to the drill during operation. Alright, so we're given some information about energy. Okay. And recall that the energy is equal to the power in terms of time. T. Now we're given the time T. But we're not given the power P. Well, let's think about this. The power P we know is related to the voltage, which we do have information about. Okay, so we can write that the energy is equal to the power which is equal to the voltage, times the current and then times at time t. Now we know the energy, we know the voltage and we know the time that's gonna allow us to find that curve. Alright, so let's plug in the values that we know 3.24 times 10 to the five jules is our energy. So that's going to be on the left hand side. Then on the right hand side we have our voltage 18 volts times our current I that we're looking for times the time T. Which we have is 15 minutes. Now we want to convert this to our standard unit of seconds. Okay, so to do that, we're going to multiply And we know that we have 60 seconds per minute. The unit of minute will divide out and we're going to be left with just a unit of seconds. And so our current I okay if we isolate, it so we're going to divide the other terms on that side, we're going to have 3.24 Times 10 to the five jewels divided by volts Times 900 seconds. And this gives us a current of 20 amps. Alright? So the average current supply to the drill during operation is going to be 20 amps and that corresponds with answer choice B. That's it for this one. Thanks everyone for watching. See you in the next video.

The battery for a certain cell phone is rated at 3.70 V. According to the manufacturer it can produce 3.15 * 10^4 J of electrical energy, enough for 5.25 h of operation, before needing to be recharged. Find the average current that this cell phone draws when turned on.

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