Question

PART A: An electron moves at 3.00×10⁶ m/s through a region in which there is a magnetic field of unspecified direction and magnitude 7.50×10⁻² T .

A1: An electron moves at 3.00×10⁶ m/s through a region in which there is a magnetic field of unspecified direction and magnitude 7.50×10⁻² T .

A2: What is the smallest possible magnitude of the force on the electron due to the magnetic field?

Express your answer in newtons to the nearest integer.

A3: If the force on the electron is half of its maximum value, what is the angle between the electron’s velocity and the magnetic field?

Express your answer in degrees to two significant figures.

PART B: A magnetron in a microwave oven emits microwaves with frequency f=2450MHz. What magnetic-field strength would be required for electrons to move in circular paths with this frequency?

If the magnetron emits microwaves with frequency 2240 MHz , what magnetic-field strength would be required for electrons to move in circular paths with that frequency?

Express your answer in tesla to three significant figures.

PART C: A beam of protons traveling at 1.20 km/s enters a uniform magnetic field, traveling perpendicular to the field. The beam exits the magnetic field in a direction perpendicular to its original direction  (Figure 1). The beam travels a distance of 1.80 cm while in the field.

What is the magnitude of the magnetic field?

Express your answer in teslas to three significant figures.

PART D: A 3.25 g bullet picks up an electric charge of 1.25 μC as it travels down the barrel of a rifle. It leaves the barrel at a speed of 403 m/s traveling perpendicular to the earth’s magnetic field, which has a magnitude of 5.50×10⁻⁴ T .

D1: Calculate the magnitude of the magnetic force on the bullet.

Express your answer with the appropriate units.

D2:Calculate the magnitude of the bullet’s acceleration due to the magnetic force at the instant it leaves the rifle barrel.

Express your answer with the appropriate units.

PART E:The world's lightest bird is the bee hummingbird; its mass is 1.6 g(less than that of a penny). As shown in (Figure 1), we design a perch for this bird that is supported by a magnetic force. The perch is 13 cm long, has a mass of 8.0 g , and contains a wire carrying a current I=4.0A. The perch is oriented at right angles to a uniform magnetic field that is just strong enough to support the perch and a bee hummingbird. What are the direction and magnitude of the magnetic field?

How massive a bird could this perch support if the current were increased to I=5.7A?

Express your answer to two significant figures and include appropriate units.

Answer 1