AP Physics L12_Hall Magnetic + Electric field Force on a charge Magnetic + Electric field

Total Force F = q (E + vB) When does the force vanish? AP Physics L12_Hall Total Force F = q (E + vB) When does the force vanish? Why is this called a velocity selector? When E is in the direction of –v x B. So E must be perpendicular to B. What are the units of vB? What are the units of E/B?

The Hall Effect

Current through a Field Charge carriers experience a force B I Where do moving charges congregate?

Positive charge carriers Positive charges accumulate B V I + + + + + + + + + + + + + + ++ + + + + + + + + + + Set up an E field ↓ Voltage across the ribbon

Negative charge carriers Negative charges accumulate B V I − − − − − − − − − − − − − − − − − − − − − − − − − − Set up an E field ↑ Voltage across the ribbon

Uses of Hall Effect Determine sign of charge of charge carrier Measure drift velocity Determine charge carrier density