5.4 Magnetic Effects of Electrical Currents

Question 1

Electric vs Magnetic Fields

Answer 1

• Electric fields are caused and affected by charges whereas magnetic fields by magnets
• Positive and negative charges attract vs north and south poles attract

Question 2

Magnetic Field Lines

Answer 2

Flux (Field) lines of the magnetic field used to help visualise a magnetic field where the direction of the force is shown by the direction of the field lines, and the strength by the distance between the field lines (closer is stronger)

Question 3

Direction of Magnetic Field due to Electric Current

Answer 3

Right-Hand Rule
Thumb down when into the page - right-hand fingers point to the direction of current
Thumb up when out of the page - right-hand fingers point to the direction of current

Question 4

Solenoid

Answer 4

A long current-carrying coil with the same field pattern as a bar magnet（can be predicted using right-hand rule)

Question 5

Magnetic Force on a Current

Answer 5

A current-carrying wire is placed in a magnetic field the magnetic where the interaction between the two results in a force called the motor effect

Question 6

Right Hand Rule with Forces

Answer 6

When dealing with a positive, moving charge, the thumb must point in the direction of the current, where the fingers point in the direction of the magnetic field. By doing this, the resultant motor force will be in the direction the palm faces. For an electron it is the back of the hand instead

Question 7

Magnetic Field Strength (B) Formula

Answer 7

B = F/(I L sinθ) or F = BILsinθ
where
F is magnetic force
I is current

Question 8

Magnetic Force on a Moving Charge

Answer 8

A single charge moving through a magnetic field also feels a force in the same way that a current feels a force

Question 9

Magnetic Field Strength in a Moving Particle

Answer 9

B = F/(q v sinθ)