A common cell phone charger operates at 6.5V and consumes of 5W of power. 12) a)
ID: 1281286 • Letter: A
Question
A common cell phone charger operates at 6.5V and consumes of 5W of power. 12)
a) What is the current flowing in the charger?
b) If it takes two hours to charge a phone completely, how much total energy was used? c) If a 1 kg particle has the same amount of kinetic energy as your answer to part (b), how fast is it moving?
d) A claim was circulated on the internet recently which stated that a smartphone uses more energy than a refrigerator. Given that refrigerators consume about 750 W of power, and assuming that a phone is charged once a day, is this claim correct? (Hint: Unsourced scientific claims circulated on the internet are rarely, if ever, true. However, to answer the question you should calculate the average wattage of the cell phone.)
Explanation / Answer
As we know that
P = VI
Therefore
I = P/V
= 5/6.5
= 0.769 A
=========================================================
Energy = P*t
= 5*2*60*60
= 36000 J
=================================================
Kinetic Energy = 0.5*m*v^2
36000 = 0.5*1*v^2
v = 268.328 m/sec
=================================================
Energy Consumed by the movile phone = P*t
= 5*2*60*60
= 36000 J
Energy Consumed by refrigerator = P*t
= 750*24*60*60
= 64800000 J
No the claim is not true Because Power consumed by refrigerator is more
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