AP Physics 2:: Magnetism Induction

What is a MAGNETIC FIELD, and what TWO types of MAGNETIC POLES exist, analogous to positive and negative electric charges?

- **A)** This concept has no actual relationship between magnetic poles and any attraction or repulsion behavior
- **B)** Magnetic poles come in THREE types, rather than just north and south
- **C)** Like magnetic poles ATTRACT each other, while opposite poles REPEL -- the reverse of the actual relationship
- **D)** A magnetic field is a region of space where magnetic forces can be detected; magnets have NORTH and SOUTH poles -- LIKE poles (north-north or south-south) REPEL, while OPPOSITE poles (north-south) ATTRACT, directly analogous to the like-repel, opposite-attract rule for electric charges

Unlike ELECTRIC CHARGES (which can exist as ISOLATED positive or negative charges), why is it IMPOSSIBLE to isolate a single MAGNETIC MONOPOLE (a magnet with only a north pole OR only a south pole, but not both)?

- **A)** Cutting a magnet in half destroys ALL magnetic properties, rather than producing two smaller complete magnets
- **B)** This concept has no actual relationship between dividing a magnet and the resulting pole configuration of the pieces
- **C)** Magnetic monopoles are actually easy to isolate, contradicting the well-established absence of observed isolated magnetic poles
- **D)** Every known magnet (no matter how many times it is cut or divided) ALWAYS has BOTH a north pole AND a south pole -- cutting a bar magnet in half produces TWO smaller magnets, each with its OWN north and south pole, rather than isolating a single pole

What is the mathematical FORMULA for the MAGNETIC FORCE on a MOVING charged particle, in terms of its charge, velocity, and the magnetic field it moves through (the LORENTZ force for magnetism)?

- **A)** F = q*v/B (dividing by magnetic field strength), rather than multiplying by it
- **B)** Magnetic force depends only on the charge's velocity, with no actual dependence on the magnetic field strength itself
- **C)** This concept has no actual mathematical relationship between magnetic force, charge, velocity, and magnetic field strength
- **D)** F = q*v*B*sin(theta), where q is charge, v is speed, B is magnetic field strength, and theta is the angle between velocity and the magnetic field -- this force is MAXIMUM when velocity is PERPENDICULAR to the field (theta=90 degrees) and ZERO when velocity is PARALLEL to the field (theta=0 degrees)

Why does the MAGNETIC FORCE on a charged particle depend specifically on the particle's VELOCITY, meaning a STATIONARY charged particle experiences ZERO magnetic force, even in the presence of a strong magnetic field?

- **A)** Magnetic force depends only on the magnetic field strength, with no actual dependence on whether the charged particle is moving or stationary
- **B)** This concept has no actual relationship between a charged particle's velocity and whether it experiences any magnetic force
- **C)** Since the magnetic force formula (F=qvB*sin(theta)) includes velocity (v) as a DIRECT MULTIPLICATIVE factor, a STATIONARY particle (v=0) will ALWAYS experience ZERO magnetic force, REGARDLESS of the magnetic field's strength -- magnetic force fundamentally requires a MOVING charge
- **D)** A stationary charged particle experiences the MAXIMUM possible magnetic force, contradicting the actual velocity-dependent nature of magnetic force

What is the RIGHT-HAND RULE, and how is it used to determine the DIRECTION of the magnetic FORCE on a POSITIVE charge moving through a magnetic field?

- **A)** The right-hand rule applies only to determining electric force direction, with no actual relevance to magnetic force direction
- **B)** This concept has no actual relationship between the right-hand rule and determining magnetic force direction on a moving charge
- **C)** Point the fingers of the RIGHT HAND in the direction of the charge's VELOCITY, then CURL them toward the direction of the MAGNETIC FIELD -- the THUMB then points in the direction of the resulting magnetic FORCE on a POSITIVE charge (for a negative charge, the force points in the OPPOSITE direction)
- **D)** The right-hand rule gives the SAME force direction for both positive and negative charges, with no actual distinction based on charge sign

Why does the MAGNETIC FORCE on a moving charged particle ALWAYS act PERPENDICULAR to the particle's VELOCITY, and what CONSEQUENCE does this have for the particle's SPEED (as opposed to its direction of motion)?

- **A)** Magnetic force acts PARALLEL to velocity, causing significant changes in the particle's speed, contradicting the actual perpendicular nature of magnetic force
- **B)** Magnetic force always causes a particle to slow down and eventually stop, rather than simply changing its direction of motion
- **C)** This concept has no actual relationship between magnetic force's perpendicular nature and its effect on a particle's speed
- **D)** Since magnetic force is always perpendicular to velocity (per the cross-product nature of F=qv x B), it can only change the particle's DIRECTION of motion, NEVER its SPEED -- this means magnetic force does ZERO WORK on a moving charged particle, since work requires a force component parallel to displacement

For a CHARGED PARTICLE moving in a CIRCULAR path due to a UNIFORM magnetic field (perpendicular to its velocity), what ROLE does the magnetic force play in this circular motion, connecting back to the earlier Circular Motion and Gravitation unit?

- **A)** The magnetic force acts as a TANGENTIAL force in this scenario, speeding up or slowing down the particle rather than curving its path
- **B)** A charged particle moving through a uniform magnetic field always travels in a STRAIGHT LINE, rather than a circular path
- **C)** Magnetic force has no actual relationship to producing circular motion for a charged particle
- **D)** The magnetic force provides the CENTRIPETAL force required to keep the charged particle moving in a circular path -- since magnetic force is always perpendicular to velocity, it continuously changes the particle's direction (toward the center of the circle) without changing its speed, exactly matching the centripetal force requirement from the earlier unit

What is the mathematical FORMULA for the MAGNETIC FORCE on a CURRENT-CARRYING WIRE placed in a magnetic field, in terms of the current, the wire's length, and the magnetic field strength?

- **A)** F = I*L/B (dividing by magnetic field strength), rather than multiplying by it
- **B)** F = I*L*B*sin(theta), where I is current, L is the wire's length within the field, B is magnetic field strength, and theta is the angle between the current direction and the field -- this formula is directly analogous to the force formula for a single moving charge, since current represents many moving charges
- **C)** This concept has no actual mathematical relationship between the force on a current-carrying wire and the current, wire length, or magnetic field strength
- **D)** The force on a current-carrying wire depends only on the wire's length, with no actual dependence on the current or magnetic field strength