Sensor Accessories Wire Coil and magnet (Product No. 3173)
500 turns Coil resistance: approx. 37 Ω Rated at 0.5 A Approx. dimensions: Internal diameter 105 mm External diameter 138 mm Height 29 mm
Two 4 mm terminals (Internal 100 nF capacitor in parallel with the coil)
500 turns of 0.355 mm diameter (about 29 SWG) insulated copper wire
Mounting thread for support rod
Support rod (made from anodised aluminium approx. 140 mm long x 9.6 mm diameter)
Data Harvest Group Ltd. 1 Eden Court, Leighton Buzzard, Beds, LU7 4FY Tel: 01525 373666 Fax: 01525 851638 e-mail: sales@data-harvest.co.uk www.data-harvest.co.uk
Magnet
DS 052 1
Data Harvest. Freely photocopiable for use within the purchasers establishment
No 4
Wire Coil
DS 052
Using the Wire Coil in an electromagnetic induction investigation This investigation measures the e.m.f. induced by a magnet falling through the Wire Coil. The best results are obtained using a strong permanent bar magnet such as the Ferrite magnet supplied or an Alnico magnet. The best results will be obtained by using the ±1 V Voltage sensor (Product No. 3162) or the ±100 mA Current sensor (Product No. 3166). Table 1: Voltage (3162)
Voltage (3161)
Range
±1 V
0 – 10 V
Resolution
1 mV
Suitability
Smart Q Sensor
Voltage (3160-12)
Voltage (3160)
Current (3166)
Current (3165)
Current (3167)
±12 V
±20 V
±100 mA
±1 A
±10 A
10 mV
10 mV
10 mV
0.05 mA
0.5 mA
10 mA
(Graph only)
Notes:
The 0 – 10 V Voltage Sensor (Product No 3161) is not suitable as it only shows positive values (so half the data will be missed).
The resolution of the ±10 A Smart Q Current Sensor (Product No. 3167) is 10 mA, so it is not suitable for this investigation.
The ±1 A Current Sensor (Product No. 3165) is not suitable for use with Scope. The lowest trigger level is 40 mA, which is higher than the maximum value normally produced by a magnet.
Magnet Start point Wire Coil
Voltage or Current sensor
Soft surface
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Wire Coil
DS 052
1.
Screw the support rod into the mounting thread on the Wire Coil and mount in a clamp and stand. To regulate the height from which the magnet will be dropped, mark a ‘start’ point on the stand. Ensure that the magnet will land on something soft.
2.
Connect a Smart Q Voltage or Current sensor to the EASYSENSE unit. Connect the 4 mm leads from the Sensor to the 4 mm terminals on the Wire Coil.
3.
Open the EASYSENSE program and select either Scope or Graph from the Home page. Set the options for recording the data (see table 2).
4.
Mark the pole of the magnet that will pass through the Coil first.
5.
Click on the Start icon to begin. Allow sufficient time to elapse for any pre-trigger samples to be taken and then drop the marked end of the magnet through the coil (from the start point marked on the stand).
Table 2: Suggested recording setups Voltage ±1 V
Voltage ±12 or 20 V
Current ±100 mA
Current ±1 A
500 ms, 1 s, 2 s
500 ms, 1 s, 2 s
500 ms, 1 s, 2 s
500 ms, 1 s, 2 s
500 μs, 1 ms, 2 ms
500 μs, 1 ms ,2 ms
500 μs, 1 ms, 2 ms
500 μs, 1 ms, 2 ms
Rises above 40 mV with a 50% pre-trigger
Rises above 0.4 V with a 50% pre-trigger
Rises above 4 mA with a 50% pre-trigger
Rises above 4 mA with a 50% pre-trigger
Interval
1 ms, 2 ms
1 ms, 2 ms
1 ms, 2 ms
Trigger mode
Normal or Single shot
Normal or Single shot
Normal or Single shot
Trigger level
Positive 40 mV with a 50% pre-trigger
Positive 0.80 V with a 50% pre-trigger
Positive 4 mA with a 50% pre-trigger
Smart Q Sensor Graph
Recording time Intersample time
Trigger level
Scope
To find a suitable trigger level for the strength of your magnet use Scope. Select a timebase of 20 ms (roll mode) and click on Start. Drop the magnet through the coil and then click on Stop. Use Zoom In (right click in the graph area) to select the event data and check the maximum (positive edge) or minimum (negative edge) value produced by the magnet. Adjust the trigger to 50% or less of this value. Pre-trigger allows for a percentage of the data to be recorded prior to the trigger point being reached. This can be used to ensure that the passage of the magnet through the coil is recorded in the middle of the logging period. Without pre-trigger it may not be possible to see all of the data. We find it best to start with a pre-trigger of 50% and adjust accordingly until the whole event is displayed on the graph.
The first part of the event has been missed; try altering the pre-trigger (e.g. from 25 to 50%) or the trigger edge (e.g. from positive to negative) or the trigger level (e.g. from 40 mV to -40 mV).
The whole event is displayed
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The last part of the event has been missed; try altering the pre-trigger (e.g. from 75 to 50%) or the trigger edge (e.g. from negative to positive) or the trigger level (e.g. from -40 mV to 40 mV).
Wire Coil
DS 052
To repeat an investigation so that more than one data set is on the same graph Method 1: Select Overlay (Graph only) and click on Start to repeat the investigation using the same set up. Method 2 Save the first set of data (File, Save). Repeat the investigation - the time interval must stay the same but the trigger condition can be altered. Use Merge with file from the File menu to combine both sets of data on the same graph (Scope and Graph).
This graph shows data from two merged data files. The first data set was recorded with an interval of 1 ms using a magnet dropped through the coil North Pole first with 40 mV positive trigger edge and 50% pre-trigger. The investigation was then repeated with the magnet dropping through South Pole first, and the trigger altered to a negative edge. The effects of gravity can clearly be seen, the second pole inducing a larger emf. Notes: The displayed range of the Sensor has been reduced using Sensor settings from the Options icon. The coil can act as an aerial to electrical noise. If the graph line is not smooth try moving the apparatus to a location where there is less induced noise.
Other Investigations
What happens to the induced e.m.f. when a magnet spins in a coil?
How does the speed of the magnet affect the induced e.m.f? This can be investigated by dropping the magnet from different heights.
Two Wire Coils can be set at a distance apart equal to their radius in a Helmholtz arrangement to generate an area of uniform magnetic field intensity between the coils. A Smart Q Magnetic Field Sensor can be used to study the magnetic field along their axis.
Measuring e.m.f. and change in magnetic field to study how rate of change of magnetic field creates voltage and current.
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Wire Coil
DS 052
Limited warranty For information about the terms of the product warranty, see the Data Harvest website at: https://data-harvest.co.uk/warranty. Note: Data Harvest products are designed for educational use and are not intended for use in industrial, medical or commercial applications.
WEEE (Waste Electrical and Electronic Equipment) Legislation Data Harvest Group Ltd are fully compliant with WEEE legislation and are pleased to provide a disposal service for any of our products when their life expires. Simply return them to us clearly identified as ‘life expired’ and we will dispose of them for you.
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