Subelement I: Power Sources— Topic 61: Batteries-2
Question 3-61I6
Element 3 (GROL)A 12.6 volt, 8 ampere-hour battery is supplying power to a receiver that uses 50 watts and a RADAR system that uses 300 watts. How long will the battery last?
Explanation
To determine how long the battery will last, first calculate the total power consumed by the devices, then the total current drawn from the battery, and finally divide the battery's capacity by this current.
1. **Calculate total power consumption:**
Receiver power = 50 W
RADAR power = 300 W
Total Power (P) = 50 W + 300 W = 350 W
2. **Calculate total current drawn from the battery:**
Using the formula P = V * I (Power = Voltage * Current), we can find the current (I).
I = P / V = 350 W / 12.6 V ≈ 27.78 Amperes
3. **Calculate battery life:**
Battery capacity is 8 Ampere-hours (Ah). Battery life is calculated by dividing capacity by the current draw.
Battery Life = Capacity / Current = 8 Ah / 27.78 A ≈ 0.288 hours
4. **Convert to minutes:**
0.288 hours * 60 minutes/hour ≈ 17.28 minutes
Therefore, the battery will last approximately 17 minutes or 0.3 hours. Option D is correct. Option B represents the current draw, not the time the battery will last.
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