Some possibly useful numbers = 8.99 x 10° N m2/C2 €0 = 8.85 x 10-12C²/Nm2 4TEO %3D = 10-7Tm/A e = 1.6 x 1019 C me = 9.11 x 10-31kg mp = 1.67 x 10-27kg %3D leV = 1.6 x 10-19 J Bonus: You saw on Monday that applying the Biot-Savart Law to a point close to a long straight current carrying wire leads to 40 21 B 4 T with the directions given by the right-hand rule. (a) A current-carrying wire oriented north-south is laid above a compass needle. If the compass deflection is 20° to the east, what is the magnitude of the magnetic field due to the current? (Note that the compass reacts to the total magnetic field, consisting of the Earth's magnetic field and the magnetic field due to the current-carrying wire. The horizontal component of Earth's magnetic field has a magnitude of about 2 x 10-6 tesla.) (b) In which direction is the current flowing? (c) Draw a picture of the current-carrying wire, the compass, and include the directions of the magnetic fields due to the wire and due to the earth. (d) If the wire is 0.5cm above the compass needle, how much current flows in the wire?

Some possibly useful numbers = 8.99 x 10° N m2/C2 €0 = 8.85 x 10-12C²/Nm2 4TEO %3D = 10-7Tm/A e = 1.6 x 1019 C me = 9.11 x 10-31kg mp = 1.67 x 10-27kg %3D leV = 1.6 x 10-19 J Bonus: You saw on Monday that applying the Biot-Savart Law to a point close to a long straight current carrying wire leads to 40 21 B 4 T with the directions given by the right-hand rule. (a) A current-carrying wire oriented north-south is laid above a compass needle. If the compass deflection is 20° to the east, what is the magnitude of the magnetic field due to the current? (Note that the compass reacts to the total magnetic field, consisting of the Earth's magnetic field and the magnetic field due to the current-carrying wire. The horizontal component of Earth's magnetic field has a magnitude of about 2 x 10-6 tesla.) (b) In which direction is the current flowing? (c) Draw a picture of the current-carrying wire, the compass, and include the directions of the magnetic fields due to the wire and due to the earth. (d) If the wire is 0.5cm above the compass needle, how much current flows in the wire?