The photograph shows a type of fish called an electric ray. Electric rays can produce an electric discharge to stun their prey. Parts of a ray's body act as cells in a battery. In a ray living in fresh water the cells are arranged in series, but for a ray living in salt water the cells are arranged in para The following results are for five cells in series. The e.m.f. of the five cells together is 6.9 V. Load resistance/52 Terminal p.d./V 3.3 2.2 the internal resistance of one cell is: ○ 4.60 Ⓒ 0430 0 240 800 Current/A 1.5