Moving Charges and Magnetism Important Questions.

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1. Q1Medium

   What is the relationship between the torque on a current loop and the angle it makes with the magnetic field?

   • A.Torque is maximized at 0 degrees
   • B.Torque is minimized at 90 degrees
   • C.Torque decreases as angle increases
   • D.Torque is constant regardless of angle
   Answer: Torque decreases as angle increases

   Explanation: The torque on a current loop is maximized when the plane of the loop is perpendicular to the magnetic field. As the angle increases, the effective component of the magnetic field acting on the loop decreases, leading to a reduction in torque.

2. Q2Medium

   What does Ampère’s Circuital Law relate to in electromagnetism?

   • A.Electric fields to charges
   • B.Magnetic fields to enclosed currents
   • C.Magnetic fields to electric fields
   • D.Electric currents to resistances
   Answer: Magnetic fields to enclosed currents

   Explanation: Ampère’s Circuital Law states that the integral of the magnetic field around a closed loop is proportional to the total current passing through the loop. This law is fundamental in understanding how currents generate magnetic fields.

3. Q3Medium

   What is the primary function of a moving coil galvanometer?

   • A.To measure temperature
   • B.To measure current or voltage
   • C.To measure resistance
   • D.To measure capacitance
   Answer: To measure current or voltage

   Explanation: A moving coil galvanometer is designed to detect and measure small currents and voltages in electrical circuits. It can be calibrated to function as an ammeter or voltmeter depending on how it is connected in the circuit.

4. Q4Medium

   What is the significance of the Biot-Savart Law in electromagnetism?

   • A.It calculates electric fields
   • B.It describes magnetic fields from currents
   • C.It relates voltage to current
   • D.It measures resistance in circuits
   Answer: It describes magnetic fields from currents

   Explanation: The Biot-Savart Law provides a mathematical framework for calculating the magnetic field produced at a point in space by a small segment of current-carrying wire. This law is essential for understanding how currents create magnetic fields in various configurations.

5. Q5Medium

   What happens to the magnetic field outside a very long solenoid?

   • A.It becomes very strong
   • B.It approaches zero
   • C.It becomes unstable
   • D.It varies with distance
   Answer: It approaches zero

   Explanation: For a very long solenoid, the magnetic field inside is uniform and strong, while the field outside is negligible, effectively approaching zero. This characteristic is crucial for applications where a confined magnetic field is needed.

6. Q6Medium

   What is the relationship between the restoring torque and the deflection in a galvanometer?

   • A.kφ = NI AB
   • B.kφ = NAB/I
   • C.kφ = I/NAB
   • D.kφ = AB/N
   Answer: kφ = NI AB

   Explanation: The equation kφ = NI AB describes how the restoring torque (k) is proportional to the deflection (φ) in a galvanometer, where N is the number of turns, I is the current, and AB is a constant. This relationship is fundamental in understanding how galvanometers operate.

7. Q7Medium

   What does the Lorentz force depend on?

   • A.Charge, velocity, and magnetic field
   • B.Current and resistance
   • C.Electric field and potential
   • D.Magnetic dipole moment
   Answer: Charge, velocity, and magnetic field

   Explanation: The Lorentz force is given by the equation F = q(E + v × B), indicating that it depends on the charge of the particle (q), its velocity (v), and the magnetic field (B). This relationship is crucial for understanding the motion of charged particles in magnetic fields.

8. Q8Medium

   What is the unit of magnetic field strength?

   • A.Newton
   • B.Tesla
   • C.Ampere
   • D.Volt
   Answer: Tesla

   Explanation: The unit of magnetic field strength is the tesla (T), named after Nikola Tesla. It is a standard SI unit used to measure the strength of magnetic fields, with the gauss being a smaller, non-SI unit often used in practical applications.

9. Q9Medium

   What does Ampère’s Circuital Law relate to?

   • A.Electric fields to charges
   • B.Magnetic fields to enclosed currents
   • C.Electric currents to voltages
   • D.Magnetic fields to electric fields
   Answer: Magnetic fields to enclosed currents

   Explanation: Ampère’s Circuital Law relates the magnetic fields generated by electric currents to the currents themselves. It is a fundamental principle in electromagnetism, similar to how Gauss's law relates electric fields to charge distributions.

10. Q10Medium

    What is the primary function of a galvanometer?

    • A.To measure voltage
    • B.To detect current flow
    • C.To generate electricity
    • D.To store energy
    Answer: To detect current flow

    Explanation: A galvanometer is primarily used to detect whether a current is flowing in a circuit. It can indicate the presence and direction of current, making it a valuable tool in electrical measurements.

11. Q11Medium

    What is the formula for the magnetic field due to a long straight wire?

    • A.B = μ₀I/(2πr)
    • B.B = I/(2πμ₀r)
    • C.B = μ₀/(2πIr)
    • D.B = 2πIr/μ₀
    Answer: B = μ₀I/(2πr)

    Explanation: The magnetic field around a long straight wire carrying current is given by the formula B = μ₀I/(2πr), where μ₀ is the permeability of free space, I is the current, and r is the distance from the wire. This relationship is crucial for understanding magnetic fields generated by currents.

12. Q12Medium

    What does the Biot-Savart Law describe?

    • A.Electric fields from charges
    • B.Magnetic fields from current-carrying conductors
    • C.Electric currents in circuits
    • D.Magnetic dipoles in fields
    Answer: Magnetic fields from current-carrying conductors

    Explanation: The Biot-Savart Law provides a mathematical framework for calculating the magnetic field generated by a current-carrying conductor. It is essential for understanding how currents produce magnetic fields in various configurations.

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