12.1 Magnetic Fields and Forces

• Magnetic fields are created by moving electric charges (i.e., electric currents).


  True
• What are magnetic fields analogous to in terms of forces on charges?

  Electric fields
• What are magnetic fields?

  Regions of magnetic force
• What creates magnetic fields?

  Moving electric charges
• Magnetic fields are created solely by moving electric charges.


  True
• Magnetic field lines indicate the direction and strength of the magnetic field.
• The magnetic force on a moving charge is perpendicular to both its velocity and the magnetic field.


  True
• Match the source of the magnetic field with its properties:

  Permanent magnets ↔️ Fixed north and south poles

  Electric currents ↔️ Follow the right-hand rule
• The angle between the velocity and the magnetic field is measured in radians
• At what angles is the magnetic force zero?

  0 and 180 degrees
• What are magnetic fields generated by?

  Moving electric charges
• Magnetic field lines flow from the north pole to the south
• Magnetic field lines are more dense where the magnetic field is stronger.

  True
• What is the magnetic force on a charge of 3 \times 10^{ - 6} C</latex> moving at $50 m / s$ perpendicular to a $2 T$ magnetic field?


  $3 \times 10^{ - 4} N$
• What is the vector form of the magnetic force equation?

  $\bold{F}_{m} =$$q (\bold{v} \times \bold{B})$
• Direction of magnetic field lines around a permanent magnet

  1️⃣ North pole

  2️⃣ Curve around

  3️⃣ South pole
• Magnetic field lines form continuous loops around a magnet.


  True
• Where do magnetic field lines start in a permanent magnet?

  North pole
• What is the magnetic force on a moving charge if its velocity is parallel to the magnetic field?

  Zero
• What unit is used to measure the strength of a magnetic field?

  Teslas
• At what angle is the magnetic force maximized?

  90 degrees
• Magnetic fields are regions of space where magnetic forces can be observed.


  True
• Match the property with the correct type of field:

  Magnetic Fields ↔️ Perpendicular to motion

  Electric Fields ↔️ Parallel to field
• What determines the direction of magnetic field lines around an electric current?

  Right-hand rule
• Magnetic field lines form continuous loops, starting at the north pole and ending at the south pole.
• The magnetic force is maximized when the angle θ is 90 degrees and the sine of the angle is 1.
• The magnetic force depends on the velocity of the charge.

  True
• Steps in applying the right-hand rule for magnetic force direction

  1️⃣ Point thumb in the direction of velocity

  2️⃣ Point fingers in the direction of magnetic field

  3️⃣ Palm indicates the direction of magnetic force
• The right-hand rule is used to determine the direction of the magnetic force on a moving charged particle.


  True
• The magnetic force is always perpendicular to both the velocity and the magnetic field.


  True
• What is the formula for the magnetic force on a current-carrying wire?

  $F_{m} =$$IlBsin\theta$
• The magnetic force on a current-carrying wire is maximized when the wire is perpendicular to the magnetic field.

  True
• Match the property with its corresponding field:

  Source: Moving electric charges ↔️ Magnetic Fields

  Source: Stationary charges ↔️ Electric Fields
• What is the direction of magnetic field lines outside a permanent magnet?

  North to South
• What is the key difference between electric and magnetic fields in terms of their sources?

  Stationary vs. moving charges
• Magnetic field lines form continuous loops starting from the north pole and ending at the south pole.
• The formula for magnetic force on a moving charge is $F_{m} =$$qvBsin\theta$, where $q$ represents the charge of the particle.
• The magnetic force on a moving charge is zero when the velocity and magnetic field are parallel or antiparallel.


  True
• What is the direction of the force vector resulting from the cross product of velocity and magnetic field vectors?

  Perpendicular to both
• The right-hand rule is used to determine the direction of the magnetic force on a moving charge.


  True