## 156. Math Puzzle $5 / 78$

A freshly charged moped battery ( $6 \mathrm{~V} / 4.5 \mathrm{Ah}$ ) is connected to a lamp with the specifications $6 \mathrm{~V}$ and $0.6 \mathrm{~W}$.

How long will the lamp light up if there are no other consumers?

Hint: Ah is the abbreviation for ampere-hour and indicates the charge or amount of electricity of the battery.
The current consumption of the lamp (6 V / 0.6 W) can be determined from the given voltage and power:

$$
I=\frac{P}{U}=\frac{0.6 \mathrm{~W}}{6 \mathrm{~V}}=0.1 \mathrm{~A}
$$

From the given battery charge (4.5 Ah), the operating time of the lamp can then be calculated:

$$
I \cdot t=4.5 \mathrm{Ah} \quad, \quad t=\frac{4.5 \mathrm{Ah}}{0.1 \mathrm{~A}}=45 \mathrm{~h}
$$

The lamp will light for 45 hours if there are no other consumers.