Quick questions on Charges in magnetic fields explained: HSC Physics Module 6

2short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.

What is the Lorentz force?

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A particle of charge

q

moving with velocity

\vec{v}

in a magnetic field

\vec{B}

experiences a force:

What is reading the radius-speed graph?

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For a fixed field and a fixed type of ion,

r = \dfrac{mv}{qB}

is a straight line through the origin: the radius is proportional to speed. The gradient equals

\dfrac{m}{qB}

, so a measured gradient plus a known mass gives the field (or a known field gives the mass) - the basis of a mass spectrometer.

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