Download Current Sensor Experiment Guide

Current Sensor
Experiment Guide
Current Sensor
Introduction:
Part of the Eisco series of hand held sensors, the current sensor
allows students to record and graph data in experiments on the go.
This sensor can be used to measure the current in parallel or series
branches of low voltage AC and DC circuits and also to investigate
the dependence of the current flow through components on the
voltage across them.
With its 4 mm plugs it can easily be connected into electric circuits.
Sensor Specs:
Range -2.5 – 2.5 A | 0.01 A resolution | 3000 max sample rate
Activity – Converting Energy to Electricity
General Background:
The Eisco Energy Conversion Kit demonstrates several ways in which different types of
energy can be converted to electrical energy. The three different processes depicted in
the kit are: electro-chemical (C cell batteries), photovoltaic (solar cells), and mechanical
(handcrank / DC generator).
The DC generator has been around since the time of Michael Faraday who discovered
the operating principle behind electromagnetic generators. Faraday’s law explains how
an electromotive force is generated in an electrical conductor that encircles a time
varying magnetic field. In the Energy Conversion Kit, a hand crank turns a magnet
inside a coil of wire. The changing magnet field produced by the motion of the magnet
induces a current in the wire, which can be measured by the Current Sensor.
The generation of electricity from a solar cell is based upon the photovoltaic effect, the
creation of electrical current upon exposure to light. The incident sunlight is absorbed by
the electrons in the valence band of the atoms in the metal, and jumps to the conduction
band and become free. The free electrons are pushed out of the metal, and produce a
current that you will measure using the Current Sensor.
The electrochemical cell is a device that creates electrical energy from chemical
reactions. The cell is made up of two half-cells which each consist of an electrode (a
conductor of electricity) and an electrolyte (a substance that allows migrations of ions
between the electrodes). Electrons flows from the negatively charged electrode, called
the anode, to the positively charged electrode, called the cathode.
Required Materials:
EISCO Current Sensor & Handheld Unit
EISCO Energy Conversion Kit [PH1321]
2 ‘C’ cell batteries
Procedure
1. Plug the red and black leads from the Eisco Current Sensor into the
correspondingly colored terminals in the Energy Conversion Kit apparatus.
2. Insert two C-cell batteries into the Energy Conversion apparatus as instructed by
the diagram on the cell holder.
3.
4.
5.
6.
Turn the rotary dial on the Energy Conversion apparatus to ‘Battery.’
Record the current in the table.
Turn the rotary dial on the Energy Conversion apparatus to ‘DC Generator.’
Turn the hand crank that is attached to the DC generator via a drive belt. Vary
the speed at which you turn the hand crank and notice the variation in the current
on the sensor. Turn the hand crank as fast as you are able. Record the
maximum current measured by the sensor in the table.
7. Turn the rotary dial on the Energy Conversion apparatus to ‘Solar Cell.’
8. Record the current produced by the solar cell. If possible, take the Energy
Conversion apparatus outdoors to make the measurement. Else, point it out a
window to achieve the maximum amount of incident sun light on the solar cell.
This obviously has best results on a sunny day.
Data
Power Source
Batteries
DC Generator
(Hand Crank)
Solar Cell
Current (A)
Questions
1. What generated the most current? What generated the least?
2. Where does the energy come from for each source? What are some reasons
why one might not want to rely on the source that created the most current.
Sample Results
These are examples of possible results. Due to the many variables involved, exact
reproduction is unlikely, but students should find similar trends.
Power Source
Current (A)
Batteries
2.5 A
DC Generator
(Hand Crank)
Solar Cell
0.3 A
0.07 A
Answers to Questions
1. The batteries generated the most current. The solar cell generated the least.
2. The current from the batteries are from a chemical process, current from the DC
generator is mechanical energy, and the solar cells current came from the sun.
The chemical process involved in the batteries is not a renewable source of
energy.
The chemical process uses up the potency of the materials.
The hand crank as a source of energy is renewable, but one’s arm will most
certainly tire at some point.
The Sun as a source of energy is fairly infinite. It does depend on the amount of
sunlight reaching the cells. And will only work for the lifetime of the Sun.