A tiny thermal micro-actuator in a medical implant is activated by passing an electric current through a thin indium wire, causing it to melt and release a spring.
The indium wire melts when a charge flow of 4.5 C4.5\text{ C}4.5 C passes through it in a time of 0.60 s0.60\text{ s}0.60 s. Calculate the current in the wire when it melts. Use the equation: current=charge flowtime\text{current} = \frac{\text{charge flow}}{\text{time}}current=timecharge flow
The mass of the indium wire is 0.035 g0.035\text{ g}0.035 g and the specific latent heat of fusion of indium is 60,000 J/kg60{,}000\text{ J/kg}60,000 J/kg. Calculate the thermal energy needed to melt the wire. Use the equation: energy=mass×specific latent heat\text{energy} = \text{mass} \times \text{specific latent heat}energy=mass×specific latent heat
The micro-actuator transfers some energy to its surroundings as it heats up and melts. How does transferring energy to the surroundings affect the total energy that must be supplied to melt the indium wire?
Practise AQA GCSE Physics Internal energy and energy transfers with exam-style questions for Foundation and Higher tier. 48 questions covering Internal energy, Temperature changes in a system and specific heat capacity, and Changes of state and specific latent heat, matched to the AQA GCSE Physics (8463) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.