An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?
Answer (2)
The problem involves identifying the correct formula for calculating finance charges using the average daily balance method.
Analyze the given options and determine the most accurate formula.
The correct formula is: Finance charge = Average daily balance x Monthly periodic rate
Therefore, the final answer is: Finance charge = Average daily balance x Monthly periodic rate
Explanation
Understanding the Problem The problem describes the calculation of finance charge using the average daily balance method. We need to identify the correct formula from the given options. The key is to understand what 'periodic rate' typically refers to in the context of finance charges.
Analyzing the Options Let's analyze the options:
Finance charge = Average daily balance x Annual periodic rate
Finance charge = Average daily balance x Daily periodic rate
Finance charge = Average daily balance x Periodic rate
Finance charge = Average daily balance x Monthly periodic rate
The most common and accurate formula uses the monthly periodic rate because finance charges are usually calculated and applied on a monthly basis. The term 'periodic rate' on its own usually implies the monthly rate.
Determining the Correct Formula Therefore, the correct formula is:
Finance charge = Average daily balance x Monthly periodic rate
Examples
Imagine you have a credit card, and the company calculates your finance charge (interest) based on your average daily balance. If your average daily balance for the month is $500 and the monthly periodic rate is 1.5%, then the finance charge would be calculated as $500 x 0.015 = $7.50. This is the amount you'd be charged in interest for that month. Understanding how finance charges are calculated helps you manage your credit card usage and avoid unnecessary fees.
To calculate the number of electrons flowing through the device, we first determine the charge using the formula Q = I × t , which gives us 450.0 C. Then, we divide this charge by the charge of a single electron (approximately 1.602 × 1 0 − 19 C ) to find that approximately 2.81 × 1 0 21 electrons flow through the device. This calculation helps us understand the significant number of electrons involved in electric current.
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