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 x 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 This answer has not been graded yet. 2. Suppose your phone's battery has a capacity of 2700 mAh and a potential difference of 3.5 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 = hours 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 Submit Answer Save Progress

Explanation / Answer

1.

The capacity here represents the amount of charge stored. this can be deduced from the units given

mA = milliampere is the unit of current

h = hour is the unit of time

we know that the product of current and time gives us the charge since

Q = i t

2.

Q = 2700 mAh = 2700 x 10-3 x 3600 A-s since 1 milli = 10-3 and 1 h = 3600 sec

hence Q = 9720 C

3.

i = 1.1 A

Q = 9720 C

t = time taken = Q/i = 9720/1.1 = 8836.4 sec = 8836.4 (1/3600) h = 2.5 h

4)

t = 24 h = 24 x 3600 sec

Q = 9720 C

i = average current = Q/t = 9720/(24 x 3600) = 0.1125 A

5)

P = i V = 0.1125 x 3.5 = 0.4 Watt

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