Physics - Module 6 - Charged Particles

What experiences forces in fields?

• Any charged object experiences a force in an electric field

• A moving charged object experiences a force in a magnetic field

When can Earth’s electric and magnetic fields be modelled as uniform?

Over small distances

How do we create a uniform electric field?

By placing two parallel plates with equal and opposite charges close to each other

How do we create a uniform magnetic field?

By using a solenoid or a series of magnets arranged properly

What is Earth’s electric field like in fine weather?

It points downwards with a strength of around 100V/m

What is Earth’s electric field like in stormy weather?

It points upwards and can be very strong

How do electric field lines show an electric field?

• They indicate direction of the field (positive to negative)

• They show strength (density of field lines)

What is potential difference?

The difference in electrical potential (voltage) between the two plates

Equation for electrical field strength?

E = ∆V / d

Electric Field Definition:

Electrostatic force per unit charge exerted on a small positive test sample

Equation for electrostatic force?

F = q x E

How do we relate acceleration of a charged particle in an electric field to Newton’s second law?

• F = qE, however F = ma according to Newton’s second law

• Therefore we can say that a = qE/m

• Acceleration can also be written as a = F/m as well as a = qE/m, linking electric force and acceleration.

What are the components of the right hand rule?

• Thumb = Direction of flow of positive charge/ direction of flow of the field.

• Fingers = Direction of the magnetic field positive to negative (palm to tips)

• Palm = Direction of force

How is work done related to kinetic energy?

Work done = Kinetic Energy gained

How does a particle experience a force in a magnetic field?

If a charged particle moves through a magnetic field and a component of its velocity is perpendicular to the magnetic field, it will experience a force.

What is the nature of the force experienced by a charged, moving particle in a magnetic field?

This force that is experienced, will always be perpendicular to the magnetic field, and perpendicular to the velocity.

When does a particle not experience a force in a magnetic field?

When it is uncharged or stationary, or when the angle o

Which plate has a higher electrical potential?

The positive plate has a higher electrical potential.

This is because the field does work ( W=qV) on the positive plate.

Equation for work done?

W=qV