The PASCO scientific Model SF-8607 Basic Current Balance and SF-8608 Current Balance Accessory are designed for investigating the magnetic force experienced by a current-carrying wire in a magnetic field. This force, often referred to as magnetic force, is dependent on four key variables: the magnitude of the current (I), the length of the wire (L), the strength of the magnetic field (B), and the angle (θ) between the field and the wire. Mathematically, this relationship is expressed by the vector cross product F_m = IL x B, or in scalar terms, F_m = ILBsinθ.
Function Description:
The SF-8607 Basic Current Balance allows users to vary three of these variables—current, wire length, and magnetic field strength—and directly measure the resulting magnetic force. When combined with the SF-8608 Current Balance Accessory, the system further enables the variation of the angle between the wire and the magnetic field, facilitating a comprehensive study of this interaction.
The core principle involves measuring the change in apparent weight of a magnet assembly when a current-carrying wire is introduced into its magnetic field. This change in weight is directly proportional to the magnetic force exerted on the wire.
Important Technical Specifications:
-
SF-8607 Basic Current Balance Components:
- Main Unit
- Six Current Loop PC boards (varying lengths)
- Magnet Assembly with six magnets
-
SF-8608 Current Balance Accessory Components:
- Current Balance Accessory Unit
- Magnet Assembly
-
Current Loop Lengths (SF-8607):
- SF 40: 1.2 cm
- SF 37: 2.2 cm
- SF 39: 3.2 cm
- SF 38: 4.2 cm
- SF 41: 6.4 cm
- SF 42: 8.4 cm
- Note: These lengths are measured at the maximum length of the current-carrying wire foil. The effective length may be slightly shorter (up to 0.2 cm for single lengths and 0.4 cm for doubled lengths).
-
Required Additional Equipment (for both models):
- DC power supply capable of supplying up to 5 A (e.g., PASCO Model SF-9584).
- DC ammeter capable of measuring up to 5 A (e.g., PASCO Model SB-9624).
- Balance capable of measuring forces with an accuracy of 0.01 gram mass equivalent (e.g., PASCO Model SE-8725 quadruple beam balance or PASCO Model SE-8709 electronic top-loading balance).
- Lab stand (e.g., PASCO Model ME-9355).
- Hook-up wires with banana plug connectors (e.g., PASCO Models SE-9750 red and SE-9751 black).
-
Current Limit for SF-8608 Current Balance Accessory: Never exceed 2.0 amps when using the SF-8608.
Usage Features:
The manual outlines four experiments designed to explore the relationship between magnetic force and the influencing variables:
-
Force versus Current (Experiment 1):
- Setup: The Main Unit is mounted on a lab stand. A Current Loop is plugged into the arms of the Main Unit, with the foil extending down. The Magnet Assembly is placed on a balance, positioned so the horizontal portion of the conductive foil passes through the pole region of the magnets without touching them. A DC power supply and ammeter are connected in series with the Current Loop.
- Measurement (Quadruple-beam balance): Measure the weight of the Magnet Assembly with no current (F₀). Then, apply current (e.g., 0.5 A) and measure the new weight (F₁). The difference (F₁ - F₀) represents the force. Repeat for increasing current increments (up to 5.0 A).
- Measurement (Electronic top-loading balance): Place the Magnet Assembly on the balance and tare it to 0.00 grams. Apply current (e.g., 0.5 A) and record the reading, which directly represents the force. If the reading is negative, reverse the leads. Repeat for increasing current increments (up to 5.0 A).
- Data Processing: Plot Force (vertical axis) versus Current (horizontal axis).
-
Force versus Length of Wire (Experiment 2):
- Setup: Similar to Experiment 1, but using different Current Loops to vary the wire length.
- Measurement: With a constant current (e.g., 2.0 A), measure the force for each of the six Current Loops.
- Data Processing: Plot Force (vertical axis) versus Length (horizontal axis).
-
Force versus Magnetic Field (Experiment 3):
- Setup: Use the shortest Current Loop. Vary the magnetic field strength by changing the number of magnets mounted on the Magnet Assembly. Ensure all north poles face the same direction.
- Measurement: With a constant current (e.g., 2.0 A), measure the force for different numbers of magnets (from one up to six).
- Data Processing: Plot Force (vertical axis) versus Number of Magnets (horizontal axis).
-
Force versus Angle (Experiment 4 - requires SF-8608 Accessory):
- Setup: The SF-8608 Current Balance Accessory Unit is integrated into the setup. The dial on the accessory unit allows for precise angular adjustments. The Magnet Assembly is aligned so the magnetic field is approximately parallel with the wires of the coil at 0°.
- Measurement: With a constant current (e.g., 1.0 A), measure the force at various angles. Rotate the dial in 5° increments from 0° up to 90°, and then from 0° down to -90°.
- Data Processing: Plot Force (vertical axis) versus Angle (horizontal axis). The expected result is a sine curve.
Maintenance Features:
- Storage of SF-8607 Magnets: To maximize the retention of field strength, it is recommended to store the SF-8607 magnets by alternating their north poles next to south poles.
- Storage of SF-8608 Magnet Assembly: The Magnet Assembly from the SF-8608 Current Balance Accessory should be stored with a "keeper" made of soft iron placed across the pole pieces. This helps to retain the magnetism of the magnets.
- Copyright and Warranty: The manual is copyrighted, but non-profit educational institutions are granted permission to reproduce it for laboratory use, provided it's not sold for profit. The product comes with a one-year limited warranty covering defects in materials and workmanship. Damage due to abuse or improper use is not covered.
- Equipment Return: For returns, PASCO scientific must be notified by letter, phone, or fax to receive a return authorization and shipping instructions. Equipment must be properly packed to prevent damage during shipment, with at least two inches of packing material between the apparatus and the carton walls, and ensuring the packing material cannot shift.
- Customer Service: For service problems, customers can call toll-free 1-800-772-8700.
Need help?
General
To Next Page