ON18 P42 Q8 Wire Torque Balance | A2 Magnetic Fields | Cambridge A Level 9702 Physics

9702/41/O/N/18: (b) A stiff copper wire is balanced horizontally on a pivot, as shown in Fig. 8.1. Sections PQ, QR and RS of the wire are situated in a uniform magnetic field of flux density B produced between the poles of a permanent magnet. The perpendicular distance of PQRS from the pivot is 7.5 cm. When a current of 2.7 A is passed through the wire, a small mass of 45 mg is placed a distance 8.8 cm from the pivot in order to restore the balance of the wire, as shown in Fig. 8.2.
#9702w18p41 #A2forceOnConductorP4 #Lv3
(i) Explain why, when the current is switched on, the current in the sections PQ and RS of the wire does not affect the balance of the wire.
(ii) The length of section QR of the wire is 1.2 cm. Calculate the magnetic flux density B
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[@aarib8594]

Great explanation, thanks a lot

[@m.imrannawaz5634]

Very nice explanation

[@kholaahmad835]

Your explanation is *chefs kiss*

[@SaadSattar22]

Hello ma'am, are questions related to torque part of the new syllabus or are they omitted??

[@abdulrehmankhalid9010]

good job

[@exopuppyhyun818]

when miss lin has nicer hands then you :(

[@sarwariqbal5690]

Ty alot

[@f.r.i.e.n.d.l.y]

can someone please explain why she used grams and not kgs

[@markrobertson7299]

She used kgs. At 25:04, she said that the mass is in mg, which is mg = g x 10^-3 = kg x 10^-3 x 10 ^ -3 = kg x 10^-6