If you examine your smartphone battery, you will likely see two numbers: the bat

Question

If you examine your smartphone battery, you will likely see two numbers: the battery's "capacity" labeled in mAh (milliamps × hours or milliamp-hours), and the battery's voltage or potential difference in V (volts).

1. What physical quantity is the battery's "capacity" measuring? Explain how you can tell.

1

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2. Suppose your phone's battery has a capacity of 2900 mAh and a potential difference of 3.7 V. What is the amount of charge, in C (coulombs), that is stored in your smartphone battery when it's fully charged?
Charge =

3. Smartphone chargers are usually labeled with their current output in A (amps). Suppose your charger delivers a current of 1.1 A. If your phone's battery is completely drained, how long will it take to fully charge the battery using your charger?
Charging time =

4. Smartphones are advertised with a certain amount of "talk time", i.e., how long the phone's battery will last if you are making a call. If your phone is advertised with 24 hours of talk time, what is the average current coming from your phone's battery while making the call?
Average current =

5. What is the average power output of your phone's battery while you're making a call?
Average power =

Explanation / Answer

1) capacity in mAh : We know that I = Q/time or Q = I(time), the units indicate that these are units for the charge.

2)Q = 2900 mAh,V = 3.7 V,

Q = ( 2900 x 10^-3 A ) (3600 seconds) = 10440 C

3)time = Q/ I = 10440 C / 1.1 A =9491 seconds apprx

4) Average I = 10440 C/ ( 24 x 3600)=120.83 mA apprx

5)P = VI = 3.7 (120.83 x10^-3)=447.1 mW apprx

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