https://www.ocr.org.uk/Images/705129-equation-sheet-physics-a.pdf","initialIndex":26,"initialQuestionWindow":[{"id":"9d9bae34-012b-42c6-8d44-f0efc3a8476e","revisionId":"bf368512-7f23-4d4f-9552-f5eacb3615e7","questionNumber":null,"questionType":"LA","specification":"A student sets up an experiment where a straight conductor is suspended between the poles of a strong magnet. The conductor is connected in series to a DC power source and a switch.","difficulty":4,"difficultyBand":"medium","totalMarks":5,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"21706db3-99a5-4840-9188-bcab6059436d","label":"a","content":"Explain what happens to the conductor when the switch is closed, describing the magnetic interactions involved.","markscheme":"- States that closing the switch causes current to flow, which generates a magnetic field around the conductor B1\n- Explains that this magnetic field interacts with the permanent magnet's field M1\n- Concludes that this interaction produces a force on the conductor, causing it to move A1","marks":3,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"motor_effect","label":"Magnetic force on a conductor","steps":[{"type":"text","order":1,"title":"Close the switch","content":"Closing the switch completes the circuit, so a current flows through the conductor. A current-carrying conductor produces a magnetic field around itself.\n\nThis is the first required point, so it earns **B1**.","highlights":[{"text":"when the switch is closed","location":"specification"}]},{"type":"text","order":2,"title":"Identify the interaction","content":"There are now two magnetic fields in the same region: the field of the permanent magnet and the field produced by the current in the conductor. These fields interact.\n\nStating this interaction earns **M1**.","highlights":[{"text":"describing the magnetic interactions involved","location":"specification"}]},{"type":"text","order":3,"title":"State the outcome","content":"The interaction between the two magnetic fields produces a force on the conductor. Because it is suspended, the conductor moves in the direction of that force.\n\nThis conclusion earns **A1**. The exact direction is not asked for, so do not guess one without being given the current and field directions.","highlights":[{"text":"Explain what happens to the conductor","location":"specification"}]}]}],"generatedAt":"2026-07-22T09:13:25.365Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]},{"id":"93e4b1b5-3a36-49be-b626-c2ca84ba4f56","label":"b","content":"A section of the conductor of length \$0.30\\text{ m}\$ is situated at right angles to a uniform magnetic field of magnetic flux density \$0.080\\text{ T}\$. When the switch is closed, the conductor experiences a magnetic force of \$0.060\\text{ N}\$. Calculate the current flowing through the conductor. Use the equation: \\\\[F = B I l\\\\]","markscheme":"- Rearranges the equation $F = BIl$ to make $I$ the subject: $I = \\frac{F}{Bl}$ (or substitutes values into the equation) M1\n- Correctly calculates $I = \\frac{0.060}{0.080 \\times 0.30} = 2.5\\text{ A}$ A1","marks":2,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"rearrange_formula","label":"Rearrange the formula","steps":[{"type":"text","order":1,"title":"Choose the unknown","content":"We need the current, $I$. The conductor is at right angles to the field, so the supplied equation applies directly: $F=BIl$.\n\nUse $F=0.060\\text{ N}$, $B=0.080\\text{ T}$ and $l=0.30\\text{ m}$.","highlights":[{"text":"situated at right angles to a uniform magnetic field of magnetic flux density \$0.080\\text{ T}\$","location":"specification"},{"text":"magnetic force of \$0.060\\text{ N}\$","location":"specification"},{"text":"Use the equation: \\\\[F = B I l\\\\]","location":"specification"}]},{"type":"hyper_latex","block":{"nodes":[{"latex":"F=\\htmlData{anchor=product}{\\color{@sky}{BIl}}"},{"latex":"\\htmlData{anchor=current}{I}=\\frac{F}{Bl}"}],"highlights":[

Magnetic Field	Force on wire (N)	Current in wire (A)
W	1.2	0.4
X	1.2	0.2
Y	2.4	1.2
Z	2.4	0.3

Magnetic Field	Force on wire (N)	Current in wire (A)
W	1.2	0.4
X	1.2	0.2
Y	2.4	1.2
Z	2.4	0.3

Uses of magnetism

Question 17

Uses of magnetism Questions

Uses of magnetism

Question 17

Uses of magnetism Questions