Soal & pembahasan || KEMAGNETAN kelas IX Semester genap

Summary

This video tutorial discusses magnetic force calculations based on two problems involving current-carrying wires in magnetic fields. The first example explains how to calculate the Lorentz force on a 12-meter wire carrying 0.02 milliampere of current in a magnetic field of 90 Tesla, resulting in a force of 2.16 × 10⁻⁴ N. The second problem asks viewers to calculate the magnetic field acting on a 5-meter wire with 2 milliampere of current and a Lorentz force of 1 N, yielding a magnetic field strength of 100 Tesla. The tutorial provides a step-by-step breakdown of the formulas and concepts, encouraging viewers to engage with the material for better understanding.

Takeaways

• 😀 The video covers a lesson about magnetism, specifically for Grade 9, Semester 2.
• 😀 The first question in the exercise involves calculating the Lorentz force on a conductor using the given formula.
• 😀 Key known values in the first problem: the length of the wire (12 m), magnetic field strength (90 Tesla), and current (0.02 mA).
• 😀 The formula used to calculate the Lorentz force is F = B * I * L.
• 😀 The current is converted from milliamps (0.02 mA) to amps (0.02 / 1000 = 2 × 10^-5 A).
• 😀 After applying the values in the formula, the calculated Lorentz force is 2.16 × 10^-4 N, which simplifies to 2.16 × 10^-2 N.
• 😀 The second problem involves calculating the magnetic field strength when the Lorentz force, current, and length of the conductor are known.
• 😀 Known values in the second problem: wire length (5 m), Lorentz force (1 N), and current (2 mA).
• 😀 The current in the second problem is converted from milliamps (2 mA) to amps (2 / 1000 = 2 × 10^-3 A).
• 😀 Using the rearranged formula B = F / (I * L), the magnetic field strength is calculated to be 100 Tesla.

Q & A

What is the Lorentz force?

The Lorentz force is the force exerted on a charged particle moving through a magnetic field. It is given by the formula F = B * I * L, where F is the force, B is the magnetic field strength, I is the current, and L is the length of the conductor.

How is the Lorentz force calculated?

The Lorentz force is calculated using the formula F = B * I * L, where B is the magnetic field strength, I is the current, and L is the length of the conductor. The values for B, I, and L are substituted into the formula to determine the force.

What are the units of the variables in the Lorentz force formula?

In the Lorentz force formula, the units are as follows: B (magnetic field strength) is measured in Tesla (T), I (current) is measured in Ampere (A), and L (length) is measured in meters (m). The resulting force (F) is measured in Newtons (N).

How does the direction of the current affect the Lorentz force?

The direction of the current affects the direction of the Lorentz force. According to the right-hand rule, if the current flows in a conductor placed in a magnetic field, the force on the conductor is perpendicular to both the direction of the current and the magnetic field.

What happens if the magnetic field is parallel to the current?

If the magnetic field is parallel to the current, the Lorentz force will be zero because the sine of the angle between the current and magnetic field is zero (F = B * I * L * sin(θ)). In this case, no force is exerted on the conductor.

What is the significance of the angle in the Lorentz force formula?

The angle between the magnetic field and the direction of the current is crucial in determining the magnitude of the Lorentz force. If the angle is 90°, the force is maximized, while if the angle is 0°, there is no force acting on the conductor.

What does it mean to convert milliampere to ampere?

Converting milliampere (mA) to ampere (A) involves dividing the value by 1000. For example, 0.02 mA is equal to 0.02 / 1000 = 2 × 10^-5 A.

In the first problem, why is the force in the order of 10^-4 N?

In the first problem, the small value of the current (2 × 10^-5 A) and the relatively small length of the conductor in comparison to the magnetic field strength (90 Tesla) lead to a small Lorentz force. Therefore, the result is in the order of 10^-4 N.

How is the magnetic field strength calculated in the second problem?

In the second problem, the magnetic field strength is calculated by rearranging the Lorentz force formula to solve for B: B = F / (I * L). Given the force (1 N), current (2 × 10^-3 A), and length (5 m), the magnetic field strength comes out to 100 Tesla.

What practical applications can the Lorentz force formula have?

The Lorentz force formula is used in the design of electric motors, generators, and other devices that rely on the interaction between magnetic fields and electric currents. It is also essential in understanding phenomena such as the motion of charged particles in a magnetic field.