Physics II 2022 PDF

Key Concepts of Electrolysis The quantity of charge (or electricity) passed for a specified time can be calculated: Q=I×t Q = quantity of charge (electricity) in coulombs (C) I = current in amperes (A) t = time (seconds) The quantity 96484 C is given the name the Faraday (or...

Key Concepts of Electrolysis The quantity of charge (or electricity) passed for a specified time can be calculated: Q=I×t Q = quantity of charge (electricity) in coulombs (C) I = current in amperes (A) t = time (seconds) The quantity 96484 C is given the name the Faraday (or Faraday Constant) and the symbol F. F is equal to the quantity of electricity carried by one mole of electrons: F = Avogadro′s Number × charge on electron in coulombs F = 6.022 × 1023 mol-1 × 1.602192 × 10-19 C F = 96484 C mol-1  Key Concepts of Electrolysis To make a current flow through a resistance there must be a voltage across that resistance. Ohm's Law shows the relationship between the voltage (V), current (I) and resistance (R). Ohm's Law can be written as: V=I×R where: V = voltage in volts (V) I = current in amperes (A) R = resistance in ohms (Ω) Ref: https://www.build-electronic- circuits.com/current-voltage-resistance/ Electrical resistivity is a fundamental property of a material that quantifies how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm.meter (Ω⋅m). Figure on the right is a schematic diagram of an experimental arrangement for measuring electrical resistivity. The electrical resistivity ρ can be calculated by: Where R is the electrical resistance of a uniform specimen of the material l is the length of the specimen A is the cross-sectional area of the specimen Electrical conductivity is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter σ (sigma). The SI unit of electrical conductivity is siemens per metre (S/m). One way of classifying solid materials is according to the ease with which they conduct an electric current; within this classification scheme there are three groupings: conductors, semiconductors, and insulators. Metals are good conductors, typically having conductivities on the order of 107 (S/m). At the other extreme are materials with very low conductivities, ranging between 10-10 (S/m) and 10-20 (S/m) these are electrical insulators. Materials with intermediate conductivities, generally from 10-6 to 104 (S/m) are termed semiconductors.  Superconductivity In 1911, while studying the properties of matter at very low temperature, the Dutch physicist Heike Kamerlingh Onnes and his team discovered that the electrical resistance of mercury goes to zero below 4.2 K (-269°C). This phenomenon was called superconductivity, and the temperature at which it occurred is called its critical temperature. This was the first observation of the phenomenon of superconductivity. Some of the important superconducting elements are; Aluminium, Zinc, Cadmium, Mercury, and Lead. Phenomenon=event (plural phenomena) Ref: http://hyperphysics.phy-astr.gsu.edu/hbase/Solids/scdis.html Superconducting wire can carry immense (extremely big) electrical currents with no heating, which allows it to generate large magnetic fields. Heike Kamerlingh Onnes realised that one of the most important applications of superconductors would be in making powerful electromagnets. Superconducting magnets are used in MRI (Magentic Resonance Imaging) which is a way of looking at the soft parts of the body. It is also possible to use superconducting magnets to produce a levitating train. Levitate = to rise and float in the air without any physical support. Ref: http://cesur.en.ankara.edu.tr/superconducting-applications  Electromagnetic Radiation In physics, electromagnetic radiation refers to the waves of the electromagnetic field, propagating (radiating=spreading) through space, carrying electromagnetic energy. Electromagnetic radiation is a form of energy that is all around us and takes many forms, such as radio waves, microwaves, X-rays and gamma rays. Sunlight is also a form of electromagnetic energy, but visible light is only a small portion of the EM spectrum, which contains a broad range of electromagnetic wavelengths. The electromagnetic spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency. The common designations (official names) are: radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays.  Light Interactions With Solids When light proceeds from one medium into another (e.g., from air into a solid substance), several things happen. Some of the light radiation may be transmitted through the medium, some will be absorbed, and some will be reflected at the interface between the two media. Ref: https://www.toppr.com/content/story/amp/refraction-of-light-48152/ Materials that are capable of transmitting light with relatively little absorption and reflection are transparent—one can see through them. Materials like air, water, and clear glass are called transparent. Translucent materials allow some light to travel through them. The light does not pass directly through the materials. It changes direction many times and is scattered as it passes through. Therefore, we cannot see clearly through them and objects on the other side of a translucent object appear fuzzy and unclear. Frosted glass and wax paper are translucent. Materials that are impervious impermeable to the transmission of visible light are termed opaque. Materials such as wood, stone, and metals are opaque to visible light. Ref: https://www.pinterest.com/pi n/237635317814325065/