Module 6 - 6.3.2 Motion Of Charged Particles

Question 1

Magnetic Flux

Answer 1

BA where
- B = magnetic flux density
- A = the area at right angles to the flux

Question 2

A Velocity Selector is a device using

Answer 2

• perpendicular magnetic and electric fields to select charged particles travelling at a specific velocity
• which leave the region of crossed fields undeflected

Question 3

Velocity Selector: The particle will travel in a straight line when

Answer 3

FB = Fe
(BQv = VQ/d = mv2/r)

Question 4

Velocity Selector: Since the force acting on a charged particle is always (3)

Answer 4

• at right angles to its motion, a centripetal force is produced
• the particle will move in a circle
• at a constant speed (no net force acting)

Question 5

Velocity Selector: If the particle is -ve charged, the conventional current direction

Answer 5

is in the opposite direction to the particle’s motion

Question 6

Velocity Selector: Increasing the velocity of the charged particle

Answer 6

increases the radius

Question 7

Velocity Selector: Increasing the charge of the charged particle

Answer 7

decreases the radius

Question 8

Mass Spectrometer (3)

Answer 8

• used to measure the mass of ions
• A uniform magnetic field is used to deflect the ions into circular paths (BQv = QE)
• uses a velocity selector