Ampere's Law Quiz with Answers: Long Straight Wire

📚 Quick Study Guide

• 🧲 Ampere's Law relates the magnetic field around a closed loop to the electric current passing through the loop.
• 📏 For a long straight wire, the magnetic field lines form concentric circles around the wire.
• 📐 The formula for the magnetic field ($B$) at a distance ($r$) from a long straight wire carrying current ($I$) is: $B = \frac{\mu_0 I}{2 \pi r}$, where $\mu_0$ is the permeability of free space ($4\pi \times 10^{-7} T \cdot m/A$).
• 🧭 The direction of the magnetic field can be determined using the right-hand rule: point your thumb in the direction of the current, and your fingers curl in the direction of the magnetic field.
• 💡 The magnetic field strength decreases as the distance from the wire increases.

Practice Quiz

1. Question 1: What does Ampere's Law relate?
   1. A) Electric field to charge
   2. B) Magnetic field to current
   3. C) Voltage to resistance
   4. D) Force to acceleration
2. Question 2: What is the shape of the magnetic field lines around a long straight wire?
   1. A) Straight lines parallel to the wire
   2. B) Concentric circles around the wire
   3. C) Spirals along the wire
   4. D) Random lines
3. Question 3: What does '$r$' represent in the formula $B = \frac{\mu_0 I}{2 \pi r}$ for a long straight wire?
   1. A) Radius of the wire
   2. B) Distance from the wire
   3. C) Resistance of the wire
   4. D) Resistivity of the wire
4. Question 4: According to Ampere's Law, if the current in a long straight wire doubles, what happens to the magnetic field at a fixed distance from the wire?
   1. A) It halves
   2. B) It doubles
   3. C) It remains the same
   4. D) It quadruples
5. Question 5: What is the value of $\mu_0$ (permeability of free space)?
   1. A) $8.85 \times 10^{-12} F/m$
   2. B) $4\pi \times 10^{-7} T \cdot m/A$
   3. C) $3 \times 10^8 m/s$
   4. D) $9.8 m/s^2$
6. Question 6: Using the right-hand rule, if your thumb points in the direction of the current, what do your fingers indicate?
   1. A) Direction of the electric field
   2. B) Direction of the magnetic field
   3. C) Direction of the electron flow
   4. D) Direction of the voltage
7. Question 7: As the distance from a long straight wire increases, what happens to the strength of the magnetic field?
   1. A) Increases linearly
   2. B) Decreases linearly
   3. C) Increases exponentially
   4. D) Decreases exponentially