Chapter 28: Problem 74
A particle with charge \(2.0 \mathrm{C}\) moves through a uniform magnetic field. At one instant the velocity of the particle is \((2.0 \hat{i}+4.0 \hat{j}+6.0 \hat{\mathrm{k}}) \mathrm{m} / \mathrm{s}\) and the magnetic force on the particle is \((4.0 \hat{\mathrm{i}}-20 \mathrm{j}+12 \mathrm{k}) \mathrm{N}_{\rightarrow}\) The \(x\) and \(y\) components of the magnetic field are equal. What is \(\vec{B} ?\)
Short Answer
Step by step solution
Understand Given Values
Use of Lorentz Force Equation
Determine \(\vec{v} \times \vec{B}\)
Equate Magnetic Force Components
Solve the System of Equations
Formulate the Magnetic Field Vector
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Lorentz Force
Cross Product
- A vector cross product is defined as:\[\vec{v} \times \vec{B} = \begin{vmatrix}\hat{i} & \hat{j} & \hat{k} \ v_x & v_y & v_z \ B_x & B_y & B_z \end{vmatrix}\]
- This is expanded to:\[\vec{v} \times \vec{B} = (v_yB_z - v_zB_y)\hat{i} - (v_xB_z - v_zB_x)\hat{j} + (v_xB_y - v_yB_x)\hat{k}\]
Charge of a Particle
- Positive charges move in opposite directions to negative charges when influenced by a magnetic field.
- The magnitude of the force is directly proportional to the charge: if you double the charge, the force doubles as well.
Vector Components
- Velocity and magnetic field vectors can be broken into components: \(v = v_x \hat{i} + v_y \hat{j} + v_z \hat{k}\).
- In the case of the magnetic field in the exercise, since \(B_x = B_y\), the components are \(B = B_x \hat{i} + B_x \hat{j} + B_z \hat{k}\).