Q2. Figure 1 shows a mobile phone being recharged by a portable power source. Figure 1 (a) Why does the battery in the phone need recharging? Tick one box. The store of chemical energy in the battery has reduced. The store of thermal energy in the battery has reduced. The store of kinetic energy in the battery has reduced. The store of gravitational energy in the battery has reduced. (b) The power source provides a current of 1.86 A at a potential difference of 3.90 V Calculate the power of the power source. Use the equation: power potential difference x current Choose the correct unit from the box. C J W Power = Unit (3) (c) A student needs a new power source. Figure 2 shows three different sized power sources. Figure 2 Compact Large The table below gives data about the different power sources. Power source Number of charges Mass in grams Compact 1 100 Large 5 200 High capacity 10 600 High capacity The student chose the large power source. Suggest why the student chose the large power source.