Motion in Combined Electric and Magnetic Fields

The video tutorial covers the concepts of a velocity selector and a cyclotron. It explains how a velocity selector uses perpendicular electric and magnetic fields to allow particles of a specific velocity to pass through undeflected, a method used by J. J. Thomson and in mass spectrometers. The cyclotron, invented by Lawrence and Livingston, is a device that accelerates charged particles using a magnetic field and alternating electric fields. The tutorial details the mechanics of the cyclotron, including the spiral motion of particles and the resonance condition. It concludes with the applications of cyclotrons in particle acceleration and bombardment.

What is the condition for a charged particle to move without deflection in a velocity selector?

• E equals v/B

• E equals vB

• E equals B

• E equals B/v

Which scientist used the velocity selector principle to measure the charge-to-mass ratio of an electron?

• Ernest Rutherford

• J. J. Thomson

• Niels Bohr

• Albert Einstein

What is the primary function of a cyclotron?

• To deflect charged particles

• To generate electric fields

• To accelerate charged particles

• To measure charge-to-mass ratio

What shape are the metallic plates inside a cyclotron?

• Circular

• D-shaped

• Square

• Triangular

What is the term for the frequency at which the cyclotron operates?

• Resonance frequency

• Cyclotron frequency

• Magnetic frequency

• Electric frequency

What happens to the radius of the particle's path as it gains energy in a cyclotron?

• It decreases

• It remains constant

• It increases

• It becomes elliptical

What is the relationship between the time for one revolution of a charged particle in a cyclotron and its speed?

• Time decreases with speed

• Time increases with speed

• Time is independent of speed

• Time varies unpredictably with speed