ull,{"backHref":"/gcse/physics/edexcel/questions","basePath":"/gcse/physics/edexcel/efficiency-and-energy-resources/questions","formulaUrl":null,"initialIndex":50,"initialQuestionWindow":[{"id":"ae270f56-501e-4717-b56b-3dffe50b1357","revisionId":"ff88a78a-a1b5-4e89-b09e-ada9dea598d8","questionNumber":null,"questionType":"LA","specification":"For a commercial tidal stream generator:\n\n- the kinetic energy input per second from the flowing tidal current is $18.5\\text{ MJ}$\n- the useful electrical energy output per second is $5.92\\text{ MJ}$.","difficulty":3,"difficultyBand":"easy","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"af90673e-b610-4beb-8791-891d4d018265","label":null,"content":"Calculate the efficiency of this tidal stream generator.","markscheme":"- Uses the formula $\\text{Efficiency} = \\frac{\\text{Useful energy output per second}}{\\text{Total energy input per second}}$ or substitutes values: $\\frac{5.92}{18.5}$ M1\n- Calculates the efficiency as $0.32$ (or $32\\%$) A1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"efficiency_ratio","label":"Use the efficiency formula","steps":[{"type":"text","order":1,"title":"Choose the quantities","content":"Both values are energies transferred **per second**, so they can be used directly in the efficiency calculation. The kinetic energy input is $18.5\\text{ MJ}$ per second and the useful electrical energy output is $5.92\\text{ MJ}$ per second.\n\nThe useful output goes on top of the fraction; the total input goes underneath.","highlights":[{"text":"the kinetic energy input per second from the flowing tidal current is $18.5\\text{ MJ}$","location":"specification"},{"text":"the useful electrical energy output per second is $5.92\\text{ MJ}$","location":"specification"}]},{"type":"hyper_latex","block":{"nodes":[{"latex":"\\text{Efficiency}=\\frac{\\htmlData{anchor=formula}{\\text{useful energy output per second}}}{\\text{total energy input per second}}\\quad\\text{(M1)}"},{"latex":"\\text{Efficiency}=\\frac{5.92}{18.5}"},{"latex":"\\text{Efficiency}=\\htmlData{anchor=answer}{0.32}=32\\%\\quad\\text{(A1)}"}],"highlights":[{"color":"green","anchor":"formula"},{"color":"green","style":"box","anchor":"answer"}]},"order":2,"title":"Substitute the energies","description":"This substitution earns M1; evaluating it gives the accepted answer for A1."}]}],"generatedAt":"2026-07-22T11:53:50.000Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"afe63539-9750-405e-8d51-7489e79e44f9","revisionId":"ceb3828d-09d6-4dbc-8d0e-9f7be8c38884","questionNumber":null,"questionType":"LA","specification":"Nuclear power is one method used to generate electricity on a large scale.","difficulty":3,"difficultyBand":"easy","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"024629e9-35d6-46cb-a0e7-0044d599546f","label":null,"content":"State **two** advantages of generating electricity using nuclear power stations compared with generating electricity using wind turbines.","markscheme":"- States that nuclear power is reliable or predictable (i.e. not dependent on weather or wind speed) [Max 2 marks overall] B1\n- States that nuclear power has a high energy density, or a smaller land footprint for the same power output B1\n- States that nuclear power can provide a constant 'base load' to the National Grid / grid stability B1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"compare_generation","label":"Compare the generation methods","steps":[{"type":"text","order":0,"title":"Use reliable output","content":"Give two **distinct** advantages over wind turbines. One mark-earning statement is:\n\n> Nuclear power is reliable and predictable because it does not depend on the wind blowing, unlike wind turbines.\n\nThis earns **B1** for reliability/predictability. It makes the comparison explicit: wind output changes when wind speed chang

Efficiency and energy resources

Question 39

Efficiency and energy resources Questions

Efficiency and energy resources

Question 39

Efficiency and energy resources Questions