Matter and Energy

Basics of Magnetism

100

100: What generates Earth’s magnetic field?

• Answer: Moving molten iron in Earth’s core.

200

200: What causes auroras like the Northern Lights?

• Answer: Collisions between solar wind particles and atmospheric gases.

300

300: What is the unit of magnetic flux density?

• Answer: Tesla (T).

400

400: What happens to the strength of a magnetic field as you move further away from its source?

Answer: The strength of the magnetic field decreases with distance from its source.

500

500: What is the formula for the magnetic force acting on a moving charge?

Answer: F=qvBsinθ.

Electric Current

100

100: What is the formula for electric current?

Answer: I=Q/t.

200

200: What is the SI unit of electric current?

• Answer: Ampere (A).

300

300: What is the difference between direct current (DC) and alternating current (AC)?

• Answer: DC flows in one direction, while AC alternates direction cyclically.

400

400: How is current density (J) defined?

Answer: J=I/A.

500

500: What is 1 Ampere equivalent to?

Answer: 1 Coulomb per second.

Ohm’s Law and Resistance

100

100: What is the formula for Ohm’s Law?

Answer: V=IR.

200

200: What does the resistance of a conductor depend on?

Answer: Length, cross-sectional area, and resistivity.

300

300: What is the relationship between resistance, voltage, and current according to Ohm’s Law?

• Answer: Resistance is equal to voltage divided by current: R=V/I.
  
  

400

400: If the length of a conductor doubles, what happens to its resistance?

• Answer: Resistance doubles.

500

500: How do you calculate the power using Ohm’s Law?

Answer: P=IV, P=I^2R, or P=V^2/R.

Circuit Analysis

100

100: In a series circuit, how do you calculate total resistance?

Answer: Req=R1+R2+R3.

200

200: In a parallel circuit, how do you calculate total resistance?

Answer: 1/Req=1/R1+1/R2+1/R3.

300

300: What does Kirchhoff’s Current Law state?

• Answer: The sum of currents entering a node equals the sum of currents leaving the node.

400

400: What does Kirchhoff’s Voltage Law state?

• Answer: The sum of voltages in a closed loop equals zero.

500

500: How do you analyze a mixed circuit?

Answer: Combine series and parallel resistances step by step to find total resistance.

Magnetic Force

100

100: What happens to magnetic force if the angle (θ) is 0∘?  

• Answer: Magnetic force is zero.

200

200: What is the maximum angle (θ) for magnetic force?

Answer:90∘.

300

300: If q=2C, v=3m/s, and B=4T, what is F at θ=90∘?

Answer:24N.

400

400: What is the unit of charge (q) in the magnetic force formula?

• Answer: Coulomb (C).

500

500: How does the magnetic force on a charged particle change if the particle’s velocity is doubled while keeping the magnetic field and charge constant?

Answer: The magnetic force will also double because force is directly proportional to velocity in the formula F=qvBsinθ.