€XXX A particle physicist observes that the path of a particle in Earth's magnetic field is a spiral as shown. The particle spirals down and to the right. The magnetic field is directed downwards. (a) Is the particle more likely to be a proton or an electron? Explain (2 marks) (b) Explain how this effect produces the northern and southern lights. (2 marks) An "electrostatic precipitator" is a pollution control device that removes tiny particles from the emissions of coal-burning power plants. It consists of positively charged plates and negatively charged wires as shown in the diagram. The electric field near the wires ionizes the air and creates free electrons which then attach to the harmful particles in the gas. (a) The electric field between the wires and plates in an electrostatic precipitator is about 1.0 x 106 N/C. Assuming this is a uniform electric field and the wire and plate are 10. cm apart, how much electric potential energy would a soot particle with three excess electrons have if it moves from the wire to the plate? (2 marks) (b) What is the electric potential difference between the wire and the plate? (2 marks)

A proton enters a region with a uniform electric field E=5.0kV/m and a uniform magnetic field B=5.0104kT. The proton has initial velocity v0=2.5105m/s. How far along the z axis does the proton travel after it undergoes three complete revolutions?

Electrons in Earths upper atmosphere have typical speeds near 6.00 105 m/s. (a) Calculate the magnitude of Earths magnetic field if an electrons velocity is perpendicular to the magnetic field and its circular path has a radius of 7.00 102 m. (b) Calculate the number of times per second that an electron circles around a magnetic field line.

An electron is projected into a uniform magnetic field (0.5i+0.8k)T with a velocity of (3.0i+4.0j)106 m/s . What is the magnetic force on the electron?

A 1.0-rn-long segment of wire lies along the x-axis and carries a current of 2.0 A in the positive x-direction. Around the sire Is the magnetic field of (3.0i4.0k)103T. Find the magnetic force on this segment.

(a) Aircraft sometimes acquire small static charges, Suppose a supersonic jet has a 0.500C charge and flies due west at a speed of 660.m/s over Earth’s south magnetic pole, where the 8.00105T -T magnetic field points straight down into the ground, What are the direction and the magnitude of the magnetic force on the plane? fb) Discuss whether the value obtained in part (a) implies this is a significant or negligible effect,

A laboratory electromagnet produces a magnetic field of magnitude 1.50 T. A proton moves through this field with a speed of 6.00 106 m/s. (a) Find the magnitude of the maximum magnetic force that could he exerted on the proton. (b) What is the magnitude of the maximum acceleration of the proton? (c) Would the field exert the same magnetic force on an electron moving through the field with the same speed? (d) Would the electron experience the same acceleration? Explain.

Neurons in our bodies carry weak currents that produce detectable magnetic fields. A technique called magnetoencephalography, or MEG, is used to study electrical activity in the brain using this concept This technique is capable of detecting magnetic fields as weak as 1.0 1015 T. Model the neuron as a long wire carrying a current and find the current it must carry to produce a field of this magnitude at a distance of 4.0 cm from the neuron.

Check Your Understanding In what orientation would a magnetic dipole have to be to produce (a) a maximum torque in a magnetic field? (b) A maximum energy of the dipole?

(a) A cosmic ray proton moving toward the Earth at 5.00107m/s experiences a magnetic force of 1.701016N. What is the strength of the magnetic field it there is a 45° angle between it and the proton’s velocity? (b) Is the value obtained in part (a) consistent with the known strength of the Earth’s magnetic field on its surface? Discuss.