12.07.2015 Views

Formula Sheet for Stage 6 Physics

Formula Sheet for Stage 6 Physics

Formula Sheet for Stage 6 Physics

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<strong>Formula</strong> Name Comments Typical Problem Typical AnswerF = BIlMagnetic <strong>for</strong>ceon a currentcarryingwire oflength l in amagnetic field9.3.1F = <strong>for</strong>ce (N)B= Magnetic Field (T)I = current (A)l = length (m)Calculate the <strong>for</strong>ce on2m of wire carrying acurrent of 4A in amagnetic field of0.1T.F = BIl= 0.1X 4X2 = 0. 8NFl= k I 1I 2dτ = rF dForce per unitlength9.3.1torque9.3.1τ = nBIAcosθ torque on a coilimmersed in amagnetic field9.3.1vpvs= n pnsTrans<strong>for</strong>merequation9.3.4F = <strong>for</strong>ce (N)l = length (m) per unitI 1 , I 2 = two currentsparallel=repulsive,antiparallel=attractived = separation of the two currents(m)k=magnetic constant (2 X 10 -7 NC -1 m -1 )τ =torque (Nm)F =<strong>for</strong>ce (N)d=distance (m)τ =torque (Nm)n =number of turns of coilB=magnetic field (T)I = current (A)A = area of coil immersed inmagnetic field (m 2 )cos Θ=angle between the coil andthe magnetic fieldV p = primary voltage (V)V s = secondary voltage (V)N p = number of turns in the primarycoilN s = number of turns in thesecondary coilWhat is the <strong>for</strong>ce perunit length on twowires, both carrying10A, separated by adistance of 3m?What is the torque ona nut when a 0.6 mspanner has a <strong>for</strong>ce of80 N applied on it?What is the torque ona 0.20 m 2 coil of 200turns immersed in amagnetic field of 0.2T carrying a currentof 3 A?A trans<strong>for</strong>mer isrequired to step downmains voltage (240V)to 12 V. If theprimary coil has 960turns, how many turnsare required in thesecondary coil?FlI I= kd= 2X1010X10X = 6.67X1031 2−7−6τ = F rd = 80 X 0.6 = 48Nmτ = nBIAcosθ= 200 X 0.2X3X0.20 = 24Nmvvpsn=nps∴nssnpv=vps960X12= = 48 turns.240N / m

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