ELECTRICITY ELECTRICITY

BDS Learning Application, 2021

In practice, we deal with charges much greater in magnitude than the charge on an electron, so we can ignore the quantum nature of charges and imagine that the charge is spread in a region in a continuous manner. Such a charge distribution is known as a continuous charge distribution. Calculation of the force on a charge due to a continuous charge distribution As shown in figure consider a point charge q0 lying near a region of continuous charge distribution. This continuous charge distribution can be imagined to consist of a large number of small charges dq. According to Coulomb's law, the force on point charge qo due to small charge dq is Force on a point charge q0 due to a continuous charge distribution.

1. Rub a glass rod with silk and use it to charge an electroscope. The electroscope will end up with a net positive charge. Bring the pocket comb close to the electroscope. If the electroscope leaves move farther apart, then the charge on the comb is positive, the same as the charge on the electroscope. If the leaves move together, then the charge on the comb is negative, opposite the charge on the electroscope. 2. The shirt or blouse becomes charged as a result of being tossed about in the dryer and rubbing against the dryer sides and other clothes. When you put on the charged object (shirt), it causes charge separation within the molecules of your skin (see Figure 21-9), which results in attraction between the shirt and your skin. 3. Fog or rain droplets tend to form around ions because water is a polar molecule, with a positive region and a negative region. The charge centers on the water molecule will be attracted to the ions (positive to negative). 4. See also Figure 21-9 in the text. The negatively charged electrons in the paper are attracted to the positively charged rod and move towards it within their molecules. The attraction occurs because the negative charges in the paper are closer to the positive rod than are the positive charges in the paper, and therefore the attraction between the unlike charges is greater than the repulsion between the like charges. 5. A plastic ruler that has been rubbed with a cloth is charged. When brought near small pieces of paper, it will cause separation of charge in the bits of paper, which will cause the paper to be attracted to the ruler. On a humid day, polar water molecules will be attracted to the ruler and to the separated charge on the bits of paper, neutralizing the charges and thus eliminating the attraction. 6. The net charge on a conductor is the difference between the total positive charge and the total negative charge in the conductor. The " free charges " in a conductor are the electrons that can move about freely within the material because they are only loosely bound to their atoms. The " free electrons " are also referred to as " conduction electrons. " A conductor may have a zero net charge but still have substantial free charges. 7. Most of the electrons are strongly bound to nuclei in the metal ions. Only a few electrons per atom (usually one or two) are free to move about throughout the metal. These are called the " conduction electrons. " The rest are bound more tightly to the nucleus and are not free to move. Furthermore, in the cases shown in Figures 21-7 and 21-8, not all of the conduction electrons will move. In Figure 21-7, electrons will move until the attractive force on the remaining conduction electrons due to the incoming charged rod is balanced by the repulsive force from electrons that have already gathered at the left end of the neutral rod. In Figure 21-8, conduction electrons will be repelled by the incoming rod and will leave the stationary rod through the ground connection until the repulsive force on the remaining conduction electrons due to the incoming charged rod is balanced by the attractive force from the net positive charge on the stationary rod. + + + + + + +-+-+-+-+

The Papers of Independent Authors. Т. 60, p. 5, 2024

Electric charge structure Annotation A mathematical model of electric charge is proposed as a solution to Maxwell's equations. Such a charge creates electrical tension in its vicinity by Coulomb's law. It is also shown that charges can be stored and carried by carriers (for example, electrons), but can be present and move independently. Electric current is a flow of charges (but not electrons) that weakens as it moves. Thus, the charge is as immaterial as energy, which can have a carrier (as in mechanics) but can be transferred in a flow that does not have a carrier (as in electrodynamics). Content 1. Electric charges in a particle 2. Electric charges in a wire References

Electrostatic Force (charges at rest): • Electrostatic force can be attractive • Electrostatic force can be repulsive • Electrostatic force acts through empty space • Electrostatic force much stronger than gravity • Electrostatic forces are inverse square law forces (proportional to 1/r 2) • Electrostatic force is proportional to the product of the amount of charge on each interacting object Magnitude of the Electrostatic Force is given by Coulomb's Law: F = K q 1 q 2 /r 2 (Coulomb's Law) where K depends on the system of units K = 8.99x10 9 Nm 2 /C 2 (in MKS system) K = 1/(4πε πε 0) where ε ε 0 = 8.85x10-12 C 2 /(Nm 2) Electric Charge: electron charge =-e e = 1.6x10-19 C proton charge = e C = Coulomb Electric charge is a conserved quantity (net electric charge is never created or destroyed!) q 1 q 2 r

Academia Biology, 2024

Eleyele Lake serves the purpose of domestic water supply, transportation, and fisheries; therefore, it is a source of food and livelihood to the artisanal fishers in Ibadan. However, various reports indicated the perturbed state of the lake, which can have adverse effects on the ecosystem services including fisheries. Therefore, this study investigated the catch per unit effort (CPUE) of fish in the Eleyele Lake and some physicochemical parameters in order to establish the status of the fisheries of the lake. Water samples were collected from the lake and analyzed. The fish catches, effective fishing effort (EFF), and CPUE of the lake were determined. The dissolved oxygen and transparency levels were not within the recommended permissible limits. Fish encountered in the lake during the study period belong to nine families and fifteen species. Cichlidae, Polypteridae, and Clariidae were the most frequently encountered families. Shannon-Weiner (2.23), Margalef (2.14) diversity indices, and Evenness (0.87) were highest during the sampling period in 2019. The EFF was 0.37 kW day−1. The mean CPUE increased from 9.55 ± 1.67 kg·kW day−1 in 2019 to 38.07 ± 30.89 kg·kW day−1 in 2021 and declined to 6.44 ± 3.02 kg·kW day−1 in 2023. The forage /carnivore ratio was 0.70 in 2019, 0.35 in 2021, and 54 in 2023 by number indicating an imbalance in the fish population. This study implies that effective management and sustainable exploitation of the fisheries in the Eleyele Lake require improvement of water quality and enforcement of a closed season.

DOAJ (DOAJ: Directory of Open Access Journals), 2007