# Flash Cards

The helical path is the path of the motion of a charged particle when enters at an angle of $\theta$ in a uniform magnetic field $B$. In this short tutorial, we explain the factors that cause this type of motion. On a moving charged particle in a uniform magnetic field, a magnetic force of magnitude $F_B=qvB\,\sin \theta$ is acted where $\theta$ is the angle of velocity vector $v$ with the magnetic field vector $B$. This is the main factor that creates a spiral or helical path. A charged particle (say, electron) can enter a region filled with uniform $B$ either with right angle $\theta=90^\circ$ or at angle $\theta$. In the former case, its path results in a ci

Read MoreHow to find acceleration from a position vs. time graph? Answer: Acceleration on a position vs. time graph can be obtained, numerically by having the initial position and velocity of a moving object Or graphically, by observing the curvature of the $x-t$ graph. A graph, looking like an upside-down bowl, represents a negative acceleration and vice versa. In this long article, we want to show you how to find constant acceleration from a position-time graph with some solved problems. You can skip this introduction and refer to the worked examples. Types of Motion: An object can move at a constant speed or have a changing velocity. Suppose you a

Read MoreProblems and Solutions about displacement and distance are presented which is helpful for high school and college students. In the following, displacement is computed for simple cases. Displacement Problems: Problem (1): An object moves from point A to B, C, and D finally, along a rectangle. (a) Find the magnitude and direction of the displacement vector of the object? (b) Find the distance traveled by that object? (c) Suppose the object returns to point A, its initial position. Now, Find the displacement and distance. Solution: (a) By definition of displacement, connect the initial (A) and final (D) points together. As shown, displace

Read MoreThe projectile motion formulas along with numerous solved examples for a better understanding of their application are presented. Definition of projectile motion: Any object that is thrown into the air with an angle $\theta$ is projectile and its motion is called projectile motion. In other words, any motion in two dimensions and only under the effect of gravitational force is called projectile motion. Projectile Motion Formulas: The following are all projectile motion equations in vertical and horizontal directions. In horizontal direction: \[\begin{aligned} \text{Displacement}&:\,\Delta x=\underbrace{\left(v_0 \cos \theta\right)}_{v_{0x}}t\\ \text{Velocity

Read MoreThe direction of the magnetic force on a moving positively charged particle or a wire carrying current $i$ in a uniform magnetic field is determined by the right-hand rules with different versions stated below. Version 1 (right-hand rule): point the fingers of your right hand in the direction of $\vec v$ and curl them (through the smaller angle) toward $\vec B$. Your upright thumb shows the cross product $\vec v \times \vec B$ or the magnetic force $\vec F_B$. This force is perpendicular to the plane of $\vec v-\vec B$ Version 2 (right-hand rule): point your fingers in the direction of $\vec B$ so that the thumb points toward the velocity $\vec v$, your palm shows the direct

Read MoreThe comparison between electric and magnetic forces in physics for high school students is presented briefly. Definition and formulas: Electric force is repulsion or attraction between two charged objects or particles, moving or at rest, and is calculated by Coulomb’s law with the following formula \[\vec{F}_E =k\,\frac{|q|\,|q^{'}|}{r^{2}}\,\hat{r}\] where $\hat{r}$ is the unit vector that indicates the direction of the electric force and $r$ is the distance between the two charges. According to Coulomb's law, this force is proportional to the product of the magnitudes of the charges that are $|q|$ and $|q'|$. But magnetic force is a repulsion

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