Electricity and Magnetism

Ferromagnetism, paramagnetism and diamagnetism

PrincipleThe aim of this experiment is to study the behaviour of nickel, tungsten, and bismuth rods in a strong, inhomogeneous magnetic field. This field is formed, for example, between cone-shaped pole pieces that sit on a permanent magnet. The rods are suspended horizontally on a long and very thin silk thread so that they can […]

RLC measuring bridge

PrincipleOhmic resistances, inductances and capacitances are determined in a Wheatstone bridge circuit operated on AC. Balancing is done aurally through headphones, using the high sensitivity of the human ear. Benefits Quickly obtain experiment results using the Wheatstone bridge Easy to tune by aural measurement relying on the sensitivity of the human ear Save time while […]

RC filters

PrincipleResistor-Capacitor (RC) circuits serve as filters for frequencies. The frequency response of the most commonly used RC filters is recorded by point-by-point measurements as well as the frequency sweep method, and displayed on the oscilloscope. The results are plotted and verified using the measure analysis software. Benefits Investigate several types of frequency filters High-resistance inputs […]

Magnetic induction

Principle A magnetic field of variable frequency and varying strength is produced in a long coil. The voltages induced across thin coils which are pushed into the long coil are determined as a function of frequency, number of turns, diameter and field strength. Benefits Huge field coil for homogenous magnetic field On-the-fly switching of the […]

Determination of the earth’s magnetic field

Principle A constant magnetic field, its magnitude and direction known, is superimposed on the unknown earth magnetic field. The earth-magnetic field can then be calculated from the magnitude and direction of the resulting flux density. Benefits Particularly homogeneous magnetic field and high flux density due to large Helmholtz coil diameter Setup with precalibrated teslameter does […]

Current balance / force acting on a current-carrying conductor with an amperemeter

Principle The force acting on a current-carrying conductor loop in a uniform magnetic field (Lorentz force) is measured with a balance. Conductor loops of various sizes are suspended in turn from the balance, and the Lorentz force is determined as a function of the current and magnetic induction. The uniform magnetic field is generated by […]

Coulomb’s law/ image charge

PrincipleA small electrically charged ball is positioned at a certain distance in front of a metal plate lying at earth potential. The surface charge on the plate due to electrostatic induction together with the charged ball forms an electric field analogous to that which exists between two oppositely charged point charges. The electrostatic force acting […]

Diffraction and Interference of Microwaves

Principle If a double-slit is positioned in the divergent microwave beam, a characteristic intensity profile results behind this double-slit. The periodicity of the intensity profile can be used to determine the wavelength of the microwaves that are used. Benefits Convenient all-in-one set includes control unit, transmitter and receiver as horn antennae, microwave probe, microwave benches, […]

Temperature dependence of different resistors and diodes with a multimeter

Principle The temperature dependence of an electrical parameter (e.g. resistance, conducting-state voltage, blocking voltage) of different components is determined. To do this, the immersion probe set is immersed in a water bath and the resistance is measured at regular temperature intervals. Benefits Onesetup to measure both electrical components and semiconducting diodes, as well as the […]

Characteristic curve and efficiency of a PEM fuel cell and a PEM electrolyser

Principle In a PEM electrolyser, the electrolyte consists of a proton-conducting membrane and water (PEM = Proton-Exchange-Membrane). When an electric voltage is applied, hydrogen and oxygen are formed. The PEM fuel cell generates electrical energy from hydrogen and oxygen. The electrical properties of the electrolyser and the fuel cell are investigated by recording a current-voltage […]

Conservation of Energy in Reflection and Transmission of Microwaves

Principle When electromagnetic waves encounter an obstacle, they are proportionately reflected, transmitted and absorbed. In this experiment, it is proved that the sum of the proportions is conserved. Benefits Convenient all-in-one set includes control unit, transmitter and receiver as horn antennae, microwave probe, microwave benches, grating, slit plates, prism, and reflection/absorption plates With the same […]

Standing Waves in the Range of Microwaves

Principle When electromagnetic waves are bounced back and forth between two reflectors, a standing wave is formed. From the wavelength of the standing wave, the frequency of the waves can be determined. Benefits Convenient all-in-one set includes control unit, transmitter and receiver as horn antennae, microwave probe, microwave benches, grating, slit plates, prism, and reflection/absorption […]

Propagation of Microwaves (Inverse Square Law)

Principle The intensity of a source of radiation, e.g. a microwave transmitter, at any given location depends on the distance of this location from the (approximately punctiform) source. Actually, due to its antenna geometry, a microwave transmitter can only be regarded as a punctiform source of radiation at long distances, which is why it is […]

Reflection, Transmission and Refraction of Microwaves

Principle When electromagnetic waves encounter an obstacle, phenomena like reflection, transmission and refraction occur. In the present experiment these phenomena are verified and described by means of microwaves. Benefits Convenient all-in-one set includes control unit, transmitter and receiver as horn antennae, microwave probe, microwave benches, grating, slit plates, prism, and reflection/absorption plates With the same […]

Polarization of Microwaves

Principle Electromagnetic waves impact on a grating whose permeability depends on the rotation plane of the wave. Benefits Convenient all-in-one set includes control unit, transmitter and receiver as horn antennae, microwave probe, microwave benches, grating, slit plates, prism, and reflection/absorption plates With the same set, all aspects of microwave physics can be studied quantitatively: polariziation, reflection, […]

Resistance, phase shift and power in AC circuits with digital function generator

PrincipleSeries circuits containing self-inductances or capacitances and ohmic resistances are investigated as a function of frequency. Measuring the electrical magnitudes with a work or power measurement instrument, real power or apparent power can be displayed directly. Benefits Quick set-up Investigate the influence of electrical components in an AC circuit. Directly measure the real or apparent […]

Rectifier circuits

PrincipleThe ripple of the output voltage of various rectifier circuits is measured as a function of the load current strength and the charging capacitance. The characteristics of a voltage stabilizer and of a multiplier are investigated. Benefits Get to know several types of rectifier circuits Suitable for vocational classes Tasks Using the half-wave rectifier: To […]

RLC circuit with Cobra4 Xpert-Link

Principle In an RLC circuit, energy is exchanged periodically between a capacitor and a coil. When the electric field of the capacitor decreases by discharge over the coil, a magnetic field is established in the coil. As soon as the capacitor is completely depleted, the current flow through the coil vanishes. The magnetic field decreases […]

Capacitor in the AC circuit with Cobra4 Xpert-Link

Principle A capacitor is connected in a circuit with a variable-frequency voltage source. The impedance and phase displacement are determined as a function of frequency and of capacitance. Parallel and series impedances are measured. Benefits Intuitive, touch-optimized software that controls all devices simultaneously Simplified implementation: all pre-settings already prepared Easy frequency setting thanks to digital […]

Inductance of solenoids

PrincipleA square wave voltage of low frequency is applied to oscillatory circuits comprising coils and capacitors to produce free, damped oscillations. The values of inductance are calculated from the natural frequencies measured, the capacitance being known. Benefits Quick, easy, and neat set-up On-the-fly switching of the numerous induction coils for quick and easy experimenting Easy […]

Induced voltage pulse and Faraday’s law of induction with Cobra4 Xpert-Link

Principle A permanent magnet drops through a coil with different velocities. The change in the magnetic flux generates an induced voltage pulse. It is shown that the total induced voltage during the entire fall is constant and therefore independent of the velocity. In respect to the magnet polarity, the induced voltage changes from plus to minus or vice versa. Benefits […]

Transformer

Principle An alternating voltage is applied to one of two coils (primary coil) which are located on a common iron core. The voltage induced in the second coil (secondary coil) and the current flowing in it are investigated as functions of the number of turns in the coils and of the current flowing in the […]

Elementary charge and Millikan experiment

Principle Charged oil droplets subjected to an electric field and to gravity between the plates of a capacitor are accelerated by application of a voltage. The elementary charge is determined from the velocities in the direction of gravity and in the opposite direction. Tasks Measurement of the rise and fall times of oil droplets with […]

Magnetostriction with the Michelson interferometer

PrincipleWith the aid of two mirrors in a Michelson arrangement, light is brought to interference. Due to the magnetostrictive effect, one of the mirrors is shifted by variation in the magnetic field applied to a sample and the change in the interference pattern is observed. Benefits See that magnetic fields can change the geometry of […]

Ferromagnetic hysteresis with Cobra4

Principle A magnetic field is generated in a ring-shaped iron core by a continuous adjustable direct current applied to two coils. The field strength Η and the flux density B are measured and the hysteresis recorded. The remanence and the coercive field strength of two different iron cores can be compared. Benefits Simple experimental setup and intuitive handling of […]

Magnetic field outside a straight conductor

Principle A current which flows through one or two neighbouring straight conductors produces a magnetic field around them. The dependences of these magnetic fields on the distance from the conductor and on the current are determined. Benefits Four different current conductors allow the observation of the magnetic field in different configurations Experimental setup allows the […]

Magnetic field inside a conductor with digital function generator

PrincipleA current is passed through an electrolyte producing a magnetic field. This magnetic field inside the conductor is measured as function of position and current by determining the induction voltage. Benefits Measure the magnetic field inside of liquid electrolytes Large unique hollow cylinder with conductive wire mesh prevents the influence of disturbing fields Easy frequency […]

Magnetic moment in the magnetic field

Principle A conductor loop carrying a current in an uniform magnetic field experiences a torque. This is determined as a function of the radius, of the number of turns and the current in the conductor loop and of the strength of the external field. Benefits Particularly homogeneous magnetic field and high flux density due to […]

Magnetic field of paired coils in a Helmholtz arrangement with a teslameter

Principle The spatial distribution of the field strength between a pair of coils in the Helmholtz arrangement is measured. The spacing at which a uniform magnetic field is produced is investigated and the superposition of the two individual fields to form the combined field of the pair of coils is demonstrated. Benefits Particularly homogeneous magnetic […]

Magnetic field of single coils / Biot-Savart’s law with a teslameter

Principle The magnetic field along the axis of wire loops and coils of different dimensions is measured with a teslameter (Hall probe). The relationship between the maximum field strength and the dimensions is investigated and a comparison is made between the measured and the theoretical effects of position. Benefits Simple setup which allows an easy […]

Semiconductor thermogenerator – Seebeck effect

Principle In a semi-conductor thermogenerator, the no-load voltage and the short-circuit current are measured as a function of the temperature difference. The internal resistance, the Seebeck coefficient and the efficiency are determined. Benefits Open design allows to fully understand function and applications Individual instruments for distinct functions (no “black box”) Key products of the experiment […]

Characteristic curves of semiconductors with Cobra4 Xpert-Link

Principle Determine the current strength flowing through a semi-conducting diode. Determine the collector current with the collector voltage for various values of the base current intensity. Benefits Fast and easy experimenting Get to know the behaviour of several types of semiconductors Detailed experiment guide with extensive explanations and step-by-step instructions Measure voltage and current simultaneously […]

Characteristic curves of semiconductors with Cobra4

PrincipleThe current-voltage characteristic of a semiconducting diode is measured. The collector current in dependency on the emitter-collector voltage is measured for different values of base current strength through a NPN transistor. Benefits Fast and easy experimenting Get to know the behaviour of several types of semiconductors Simplified implementation: all pre-settings already prepared Data logging reveals instantaneous […]

Characteristic curves of a solar cell

Principle The current-voltage characteristics of a solar cell are measured at different light intensities, the distance between the light source and the solar cell being varied. The dependence of no-load voltage and short-circuit current on temperature is determined. Benefits Set-up allows quantitative measurement which also takes light intensity into account Set-up allows to avoid but […]

Kirchhoff’s laws

Principle Kirchhoff’s laws are verified by measuring current, voltage and resistance in series and parallel circuits. In addition, the Wheatstone bridge circuit is used to determine unknown resistances more precisely. Benefits Setup to measure both Kirchhoff’s laws and to determine unknown resistances Components can also be used for other basic and advanced electricity experiments Tasks […]

Wheatstone bridge

Principle The Wheatstone bridge circuit is used to determine unknown resistances. The total resistance of resistors connected in parallel and in series is measured. Benefits Highly precise and reproducible measurements possible Many different measurement variations possible Also suitable for measurement of low resistances Tasks Determination of unknown resistances. Determination of the total resistance of resistors […]

4 Point Method / Measurement of low resistances / Ohm’s Law

Principle The resistances of various DC conductors are determined by recording the current / voltage characteristic. The resistivity of metal rods and the contact resistance of connecting cords are calculated. Benefits Measurement at two different metals possible Conductivity rods can be used both for electrical and thermal conductivity experiments Measurement amplifier can be used for […]

Dielectric constant of different materials

PrincipleThe electric constant is determined by measuring the charge of a plate capacitor to which a voltage is applied. The dielectric constant is determined in the same way, with plastic or glass filling the space between the plates. Benefits Supplies non-hazardous high voltage Easy experimental set-up due to clear and compact design Clever investment: The […]

Capacitance of metal spheres and of a spherical capacitor

PrincipleMetal spheres with different radii and a spherical capacitor are charged by means of a variable voltage. The induced charges are determined with a measuring amplifier. The corresponding capacitances are deduced from voltage and charge values. Benefits Supplies non-hazardous high voltage Several conductive spheres included Clever investment: The included universal measuring amplifier can also be […]

Charging curve of a capacitor and switch-on behaviour of an inductance with Cobra4 Xpert-Link

Principle A capacitor is charged by way of a resistor. The current is measured as a function of time and the effects of capacitance, resistance and the voltage applied are determined. Benefits Simple and very clear set-up: only few components required Cost savings: Xpert-Link provides all subsidiary functions (power supply, switch, trigger) Extra experiment included: […]

Charging curve of a capacitor / charging and discharging of a capacitor

Principle A capacitor is charged by way of a resistor. The current is measured as a function of time and the effects of capacitance, resistance and the voltage applied are determined. Benefits Simple and very clear set-up: only few components required Further experiments in electricity and electronics can be performed with the equipment Tasks To […]

Electron spin resonance

Principle With electron spin resonance (ESR) spectroscopy compounds having unpaired electrons can be studied. The physical background of ESR is similar to that of nuclear magnetic resonance (NMR), but with this technique electron spins are excited instead of spins of atomic nuclei. The g-factor of a DPPH (Diphenylpikrylhydrazyl) specimen and the halfwidth of the absorption line […]

Coulomb potential and Coulomb field of metal spheres

Principle Conducting spheres with different diameters are charged electrically. The static potentials and the accompanying electric field intensities are determined by means of an electric field meter with a potential measuring probe, as a function of position and voltage. Benefits Supplies non-hazardous high voltage Loss-less measurement of electric field strength High-sensitive electric field meter also […]

Electric fields and potentials in the plate capacitor

PrincipleA uniform electric field E is produced between the charged plates of a plate capacitor. The strength of the field is determined with the electric field strength meter, as a function of the plate spacing d and the voltage U. The potential ø within the field is measured with a potential measuring probe. Benefits Loss-less measurement of electric field […]

Inductance of solenoids with Cobra4 Xpert-Link

Principle A square wave voltage of low frequency is applied to oscillatory circuits comprising coils and capacitors to produce free, damped oscillations. The values of inductance are calculated from the natural frequencies measured, the capacitance being known. Benefits On-the-fly switching of the numerous induction coils for quick and easy experimenting Intuitive, touch-optimized software that controls […]