lIndex":21,"initialQuestionWindow":[{"id":"5ec0b684-eb52-400d-87e8-e5b2fd34df63","revisionId":"cf5b8d15-5b64-4bdf-9ba7-8baecb14a108","questionNumber":null,"questionType":"LA","specification":"","difficulty":6,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"238d8dc2-dec7-467f-bb00-37a4a0fbc4f5","label":null,"content":"An electric delivery van's battery is recharged at a depot charging station.\n\nThe charging station provides an average current of 40.0 A to the battery, at a potential difference of 400 V.\n\nIt is claimed that 115.2 MJ of energy can be transferred to the battery in less than 1.8 hours.\n\nComment on this claim.\n\nUse this equation to support your answer:\n\n$$t = \\frac{E}{I \\times V}$$","markscheme":"- Converts energy to joules: $115.2\\text{ MJ} = 1.152 \\times 10^8\\text{ J}$ OR converts time to seconds: $1.8\\text{ hours} = 6480\\text{ s}$ B1\n- Calculates the time required as $7200\\text{ s}$ (or $2.0\\text{ hours}$) OR calculates the maximum energy transferred in $1.8\\text{ hours}$ as $103.7\\text{ MJ}$ (or $1.04 \\times 10^8\\text{ J}$) M1\n- Concludes that the claim is incorrect since $2.0\\text{ hours}$ is greater than $1.8\\text{ hours}$ (or $104\\text{ MJ}$ is less than $115.2\\text{ MJ}$) A1","marks":3,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"calculate_charging_time","label":"Calculate the charging time","steps":[{"type":"text","order":1,"title":"Convert the energy","content":"The equation uses energy in joules, so convert megajoules first:\n\n$$115.2\\text{ MJ}=1.152\\times10^8\\text{ J}$$\n\nThis unit conversion earns the **B1** mark.","highlights":[{"text":"115.2 MJ of energy","location":"specification"}]},{"type":"hyper_latex","block":{"nodes":[{"latex":"t=\\frac{E}{I\\times V}"},{"latex":"t=\\frac{1.152\\times10^{8}}{40.0\\times400}"},{"latex":"t=\\htmlData{anchor=time}{7200\\ \\mathrm{s}}"}],"highlights":[{"color":"green","style":"box","anchor":"time"}]},"order":2,"title":"Substitute the values","description":"Put the energy in joules, current in amperes and potential difference in volts into the supplied equation."},{"type":"text","order":3,"title":"Convert the time","content":"There are $3600\\text{ s}$ in one hour, so\n\n$$7200\\text{ s}=2.0\\text{ hours}$$\n\nFinding the required time earns the **M1** mark."},{"type":"text","order":4,"title":"Judge the claim","content":"The required charging time is $2.0\\text{ hours}$, which is greater than $1.8\\text{ hours}$.\n\nTherefore, the claim is **incorrect**: transferring $115.2\\text{ MJ}$ takes longer than $1.8\\text{ hours}$. This comparison and conclusion earn the **A1** mark.","highlights":[{"text":"in less than 1.8 hours","location":"specification"}]}]}],"generatedAt":"2026-07-22T09:35:37.363Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"68f31301-0d7d-4176-bba7-453c15a72158","revisionId":"64337416-0556-4cc7-84f1-c8626b719bde","questionNumber":null,"questionType":"LA","specification":"A domestic air-source heat pump has an electrical power input of $3200\\text{ W}$.","difficulty":4,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"fde2ee0d-d983-42fe-b51a-53f0ffebc55b","label":null,"content":"Show that the heat pump uses $8.64\\text{ MJ}$ of electrical energy when running continuously for $45\\text{ minutes}$.","markscheme":"- Converts time from minutes to seconds: $t = 45 \\times 60 = 2700\\text{ s}$ M1\n- Recalls and uses $\\text{Energy} = \\text{Power} \\times \\text{time}$ with $P = 3200\\text{ W}$ and their calculated time in seconds M1\n- Obtains $8,640,000\\text{ J}$ and shows conversion to $8.64\\text{ MJ}$ by dividing by $1,000,000$ A1","marks":3,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"power_times_time","label":"Use power and time","steps":[{"type":"text","order":0,"title":"Choose the equ

Electrical power

Question 7

Electrical power Questions

Electrical power

Question 7

Electrical power Questions