22.5 Force on a Moving Charge in a Magnetic Field: Examples and Applications

A wire oriented north-south carries current south. The wire is immersed in the Earth’s magnetic field, which is also oriented north-south (with a horizontal component pointing north). The Earth’s magnetic field also has a vertical component pointing down. What is the direction of the magnetic force felt by the wire?

1. West
2. East
3. Up
4. North

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A cosmic ray electron moves at $7 . \text{50} \times \text{10}^{6} \text{m}/\text{s}$ perpendicular to the Earth’s magnetic field at an altitude where field strength is $1 . \text{00} \times \text{10}^{- 5} T$. What is the radius of the circular path the electron follows?

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(a) Viewers of Star Trek hear of an antimatter drive on the Starship Enterprise. One possibility for such a futuristic energy source is to store antimatter charged particles in a vacuum chamber, circulating in a magnetic field, and then extract them as needed. Antimatter annihilates with normal matter, producing…

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What radius circular path does an electron travel if it moves at the same speed and in the same magnetic field as the proton in the exercise?

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An electron in a TV CRT moves with a speed of $6 . \text{00} \times \text{10}^{7} \text{m}/\text{s}$, in a direction perpendicular to the Earth’s field, which has a strength of $5 . \text{00} \times \text{10}^{- 5} T$. (a) What strength electric field must be applied perpendicular to the Earth’s field to make the electron moves in a straight line? (b) If this is done between plates separated by 1.00 cm…

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A mass spectrometer is being used to separate common oxygen-16 from the much rarer oxygen-18, taken from a sample of old glacial ice. (The relative abundance of these oxygen isotopes is related to climatic temperature at the time the ice was deposited.) The ratio of the masses of these two ions is 16 to 18, the…