UnitExam4Csolutions

UnitExam4Csolutions - ID: C UCSD Physics 2B Answer Section...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
ID: C 1 UCSD Physics 2B Unit Exam 4C Magnetism & Induction Answer Section MULTIPLE CHOICE 1. ANS: C B = μ 0 In = 0 IN / L L = 0 IN B = 1.26 × 10 6 H / m Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ 3.5 A () 69 3.5 × 3 T = 8.7 × 2 m TOP: SOLENOID 2. ANS: A The magnetic flux is the product of the coil area A , the number of turns N , the magnetic field strength B and the cosine of the angle at which the field lines penetrate the coil: Φ= N B A = NBA cos θ N = Φ BA cos = 0.75 Wb 0.5 T × 2 Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ 2 cos60 = 300 TOP: FLUX 3. ANS: C Lenz's Law says that the induced current flows in such a way as to oppose the change in magnetic field. As the magnet falls through the copper tube, current begins to swirl beneath it making its own magnetic field which points in the opposite direction, slowing the magnet's fall. TOP: LENZ DEMO 4. ANS: B The magnetic moment of the coil = NIA = NI π R 2 Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ The torque on the coil τ = × B = Bsin ϑ = NI R 2 Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ = 200 7.5 A 3.14 25 × 2 m Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ 2 0.35 T sin53 = 82 N m TOP: DIPOLE TORQUE 5. ANS: C = = R 2 Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ = 2 2.5 A × 2 m Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ 2 = 0.157 A m 2 TOP: DIPOLE MOMENT
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ID: C 2 6. ANS: C Force between two parallel wires of length L separated by distance r carrying different currents : F = μ 0 I 1 I 2 L 2 π r . So force per unit length for two wires carrying the same current: F L = 0 I 2 2 r = 1.26 × 10 6 H / m Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ A () 2 23 .14 0.01 m = 2.01 × 3 N m TOP: PARALLEL WIRES 7. ANS: A F = q v × B whose magnitude F = qvB sin ϑ .
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

UnitExam4Csolutions - ID: C UCSD Physics 2B Answer Section...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online