WIEDEMANN-FRANZ LAW Wiedemann-Franz law is the law which relates the thermal conductivity (κ) and the electrical conductivity (σ) of a material which consists of somewhat freely moving electrons in it. Thermal conductivity (κ): It is the degree (measure) of capacity of a material to conduct heat. Electrical conductivity (σ): It is the degree (measure) of capacity of a material to conduct electricity. ( 1/ρ) In metals; when temperature increases, the velocity of free electrons increases and that leads to an increase in heat transfer and it also increases the collisions between the lattice ions and free electrons. This results in the drop in electrical conductivity.
In 1843 James Joule read his paper to the British Association, entitled "On the Calorific Effects of Magneto-Electricity and on the Mechanical Value of Heat." This paper described the physical constant that showed that heat was a form of energy. This constant is known as "J", or "Joule's Equivalent." The unit of heat, work and internal energy are measured in joules (J). James Prescott Joule died October 11 in 1889.
The total resistance in a series circuit is sum of all the resistances Ohm's law is the mathematical relationship between the voltage, current and resistance in an electric circuit. This law states: Voltage (V) = amps (I) x Ohms (R) V=IR The relationship between heat and resistance is demonstrated by the fixed resistor and filament light bulb experiments. When a filament light bulb is used more heat is created than when a fixed resistor was used. Therefore the filament light bulb graph has a curve, while the fixed resistor graph produces a straight line. In these graphs resistance is the gradient or voltage (v)/ current (I).
Numerous factors influence electrical conductivity and resistance, two of them are temperature and length of the wire (these are external factors). Electrical conductivity is defined as the property used to describe how well materials allow electrons to flow, and the degree to which a specific material conducts electricity., Electrical conductivity is calculated as the ratio of the current density in the material to the electric field that causes the flow of current. The SI unit of electrical conductivity is Siemens per meter (S/m). Electrical conductivity is also commonly represented by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) or γ (gamma) are alsowhich are occasionally used. Electrical resistivity quantifies how strongly a specific material opposes the flow of electric current.
It was concerned with thermodynamic states, and properties as energy, work, and heat, and with the two laws of thermodynamics. However, classical thermodynamics lacked an atomic interpretation of the processes. Classical thermodynamics derives from the research done by physicist Robert Boyle. He developed the concept that the pressure P of a given quantity of gas varies inversely to its volume V at constant temperature. In other words this equation was derived: PV = k, a constant.
The y-intercept of Fig.5 suggests a systematic error associated with each measurement. This is most likely due to thermal effects which tend to randomize the directions of the magnetic moments and oppose the alignment of the magnetic moment with the magnetic field. A prolonged amount of current traveling though the apparatus would dissipate over time resulting in a change in temperature. The temperature dependence of paramagnetic material is related by Curie’s law where is the magnetization of the material, proportional to , and is the Curie constant. An increase in temperature would result in a decrease in the measured magnetic moment and a smaller calculated g-factor.
How is resistance measured? =========================== Resistance is measured in ohms (W) using an ohmmeter ( W ). Ohms Law ======== Resistance is worked out using the following scientific model (Reference from Roger Muncaster's A level Physics): r = resistivity (Wm) l = length (cm) A = Cross sectional area (cm ) K = Constant R=rl A If r and A are fixed by choosing one type of wire of one diameter then: R= k x l [IMAGE] R l Investigation- The affect of length on resistance Prediction ========== I think that as the length of a wire increases, so does the resistance. Therefore, the resistance will be directly proportional. I think this because if there is a fixed potential difference (measured in volts) across a length of conductive material it will result in a flow of electrons.
It is found that an increase in the velocity slip parameter causes decrease in the flow velocity, however an increases in the value of the thermal slip parameter causes increase in the temperature of the fluid. Ramesh et al.  studied analytically flows of Casson fluid with slip boundary conditions. Eldabe et al.  studied the problem of the boundary layer flow of MHD non-Newtonian nanofluid with heat and mass transfer through a porous medium under the effect of heat generation, radiation and chemical reaction through a porous medium.
Sensible heat is the heat acquired by transfer from an object of higher temperature. These various types of heat energy can be transferred in different forms such as conduction, convection and radiation. Conduction is the transfer of heat from one molecule to another within a substance. How fast this heat moves depends on the whether the material is a good conductor or not. Air is a poor conductor of heat so any form of heat transfer using conduction it is done near the earth’s surface.
The tesla is the SI derived unit of magnetic field strength or magnetic flux density, commonly denoted as B. One tesla is equal to one weber per square metre, VOLT The volt is the derived unit for electric potential, electric potential difference, and electromotive force. One volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. Alessandro Volta (February 18, 1745 – March 5, 1827) was an Italian physicist who was known for inventing the battery. Volta is also known for making discoveries on electrostatics and meteorology.