Ch 26: Magnetic Fields and ForcesSee all chapters
All Chapters
Ch 01: Units & Vectors
Ch 02: 1D Motion (Kinematics)
Ch 03: 2D Motion (Projectile Motion)
Ch 04: Intro to Forces (Dynamics)
Ch 05: Friction, Inclines, Systems
Ch 06: Centripetal Forces & Gravitation
Ch 07: Work & Energy
Ch 08: Conservation of Energy
Ch 09: Momentum & Impulse
Ch 10: Rotational Kinematics
Ch 11: Rotational Inertia & Energy
Ch 12: Torque & Rotational Dynamics
Ch 13: Rotational Equilibrium
Ch 14: Angular Momentum
Ch 15: Periodic Motion (NEW)
Ch 15: Periodic Motion (Oscillations)
Ch 16: Waves & Sound
Ch 17: Fluid Mechanics
Ch 18: Heat and Temperature
Ch 19: Kinetic Theory of Ideal Gasses
Ch 20: The First Law of Thermodynamics
Ch 21: The Second Law of Thermodynamics
Ch 22: Electric Force & Field; Gauss' Law
Ch 23: Electric Potential
Ch 24: Capacitors & Dielectrics
Ch 25: Resistors & DC Circuits
Ch 26: Magnetic Fields and Forces
Ch 27: Sources of Magnetic Field
Ch 28: Induction and Inductance
Ch 29: Alternating Current
Ch 30: Electromagnetic Waves
Ch 31: Geometric Optics
Ch 32: Wave Optics
Ch 34: Special Relativity
Ch 35: Particle-Wave Duality
Ch 36: Atomic Structure
Ch 37: Nuclear Physics
Ch 38: Quantum Mechanics

Concept #1: Force on Moving Charges & Right Hand Rule

Example #1: Force on Charge Moving at an Angle

Practice: An electron is moving in a straight line (red line below) when it enters the horizontal 0.2 T magnetic field (blue lines). The angle shown below is 37°. If the electron experiences a 10-12 N force upon entering the field, how fast must it be moving?

Additional Problems
A particle with negative charge q is moving to the right and enters a region where the magnetic field is uniform and directed into the page. If the particle moves through the region with constant velocity, the electric field in the region has direction (a) into the page (b) out of the page (c) to the left (d) to the right (e) toward the top of the page (f) toward the bottom of the page
A particle having a mass of 0.195 g carries a charge of -2.50x10 -8 C. The particle is given an initial horizontal northward velocity of 4.00x10 4 m/s. What are the magnitude and direction of the minimum magnetic field that will balance the Earth's gravitational pull on the particle? Hint: The velocity and the gravitational force are perpendicular.
A +2 μC charge is at rest in a magnetic field of 2 T pointing along the +x-axis. What is the force acting on this charge in the magnetic field? A) -4 μN B) +4 μN C) +2 μN D) 0
A uniform magnetic field of magnitude 0.80 T in the negative z-direction is present in a region of space. A uniform electric field is also present. In Figure 1, the electric field is set at 11,200 V/m in the positive y-direction. An electron is projected with an initial velocity vo = 1.4 x 104 m/s in the positive x-direction. The y-component of the initial force on the electron is closest to: A) +2 x 10-15 N B) -2 x 10-15​ N C) +4 x 10-15​ N D) zero E) -4 x 10-15​ N
A  -5 nC charges moves with a velocity v =  (10 m/s) î - (20 m/s) ĵ in the presence of a uniform magnetic field B = (-1.5 mT) î + (0.5 mT) ĵ. What is the magnetic force acting on the charge, both magnitude and direction?
A  2.5 μC charge with a mass of 250 μg enters a uniform, 1.5 T magnetic field. If the charge moves in the +x-direction at 150 m/s and the magnetic field points upwards, answer the following questions: a. What is the magnitude of the force on the charge? b. What is the acceleration of the charge? c. After 10 ms, what is the speed of the charge?
A particle with negative charge is traveling to the left with speed v. The particle passes through a region between two horizontal plates that carry equal and opposite charges, as shown in the sketch. Gravity can be neglected. The direction of the minimum magnetic field in the region between the plates that allows the particle to pass through the region undeflected is A) into the page B) out of the page C) to the left D) to the right E) toward the top of the page F) toward the bottom of the page
At a given instant in time, an electron and a proton are moving directly toward each other at the same speed in a uniform magnetic field that is oriented 90° from the velocities of the particles. They experience magnetic forces which are: A. equal in magnitude but perpendicular to each other. B. identical C. equal in magnitude but opposite in direction. D. in opposite directions and differing in magnitude by a factor of 1840. E. in the same direction and differing in magnitude by a factor of 1840.
A positive charge is moving to the right and experiences a vertical (upward) magnetic force, in which direction is the magnetic field? A) to the right B) upward C) to the left D) into the page E) out of the page