Electric Circuits Legacy Problem #1 Guided Solution
Problem*
Over the course of an 8-hour day, 3.8x104 C of charge pass through a typical computer (presuming it is in use the entire time). Determine the current for such a computer.
Audio Guided Solution
Current is defined as the rate at which charge passes a point on a circuit. As such, it's the ratio of the quantity of charge per time. It's the Q per T, where Q equals the quantity of charge in coulombs, and T is the time, usually expressed in units of seconds. Here we have the time as 8 hours. If we divided 8 into the 3.8 times 10 to the 4th coulombs, we would indeed have a current, however it would not be in the usual customary units of coulombs per second, or an ampere. So our first step would be to take the 8 hours and to convert that into seconds by multiplying by 60 to get the minutes, and by 60 again to get the seconds, and then taking the ratio of the coulombs per second. This would give us a current in units of coulombs per second, also known as an ampere.
Solution
1.3 A
Habbits of an Effective Problem Solver
- Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
- Identify the known and unknown quantities and record them in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., \(\descriptive{\text{δV}}{δV,change in voltage} = 9.0\unit{\volt}\); \(\descriptive{R}{R,resistance} = 0.025\unit{\ohm}\); \(\descriptive{I}{I,current} = \colorbox{gray}{Unknown}\).
- Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
- Identify the appropriate formula(s) to use.
- Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.
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