A hand-cranked emergency radio is operated to recharge its internal lithium-ion battery.
Complete the energy transfer diagram below by identifying the forms of energy at each stage:
Kinetic energy from hand cranking⟶[ Energy Form 1 ] energy in the generator circuit⟶[ Energy Form 2 ] energy stored in the battery \text{Kinetic energy from hand cranking} \longrightarrow [\ \text{Energy Form 1}\ ] \text{ energy in the generator circuit} \longrightarrow [\ \text{Energy Form 2}\ ] \text{ energy stored in the battery} Kinetic energy from hand cranking⟶[ Energy Form 1 ] energy in the generator circuit⟶[ Energy Form 2 ] energy stored in the batteryIt takes 15 minutes15\text{ minutes}15 minutes of continuous cranking at a steady rate to fully charge the battery from flat. The average current delivered by the generator is 450 mA.
(i) State the equation linking charge, current, and time.
(ii) Calculate the amount of charge needed to fully charge the battery, and state the unit.
When the user turns the crank more slowly, the output power of the generator decreases while the voltage delivered to the battery remains constant. Explain how this affects the time needed to fully charge the battery.