Electricity | Grade 8 Science DepEd MELC Quarter 1 Module 5 Part 2 Ohm’s Law

[Music] hi there in our previous video we talked about electricity and the basic concepts of current voltage and resistance in this video we are going to discuss how these three affect each other by tackling ohm's law if you haven't watched the previous discussion you can pause this video and watch that one first the relationship between voltage current and resistance in any dc electrical circuit was first discovered by george rom george ohm found that at a constant temperature the electrical current flowing through a fixed linear resistance is directly proportional to the voltage applied across it and also inversely proportional to the resistance this forms the basis of ohm's law take note that ohm's law is only applicable if there is a constant temperature once temperature changes there will be changes to the resistance as well as temperature increases resistance increases at the same time when a material gets hotter the atoms in the material vibrate more as we have discussed in our previous module about heat this makes it difficult for the electrons to move without interaction with an atom thus increasing resistance ohm's law stated that the electrical current flowing in a circuit is directly proportional to the voltage and inversely proportional to the resistance this means that if the voltage is increased then the current will increase as long as the resistance doesn't change if the resistance is increased and the voltage remains the same then the current will decrease in equation current represented by the capital letter i is equal to voltage represented by the capital letter v divided by resistance represented by the capital letter r now take note of the units of measurement for these quantities for current it is amperes or amps for short represented by the capital letter a volts for voltage represented by the capital letter v and ohms for resistance represented by the greek letter omega by knowing any two values of the voltage current or resistance quantities we can use ohm's law to find the third missing value ohm's law is used extensively in electronics formulas and calculations so it is very important to understand and accurately remember these formulas this formula is only applicable if we are looking for the current but what if we are asked to look for the voltage we use this base formula and transform it so we can look for the voltage to look for voltage multiply both sides by resistance to balance the equation now we can cancel out the resistance on the right side which leaves us with voltage now we have resistance times current equals voltage or voltage equals current times resistance to look for resistance we use this base formula we derived for voltage we divide both sides by current to balance the equation now we can cancel out current on the right side which leaves us only resistance we have voltage divided by current equals resistance or resistance equals voltage divided by current to help you memorize these formula remember the ohm's law triangle with this triangle you have memorized all three equations in one to look for voltage we can see the equation current times resistance below to look for current we can see the equation voltage divided by resistance on the right side [Music] and lastly to look for resistance we can see the equation voltage divided by current on the left side with this triangle it will be easier to memorize the formulas in ohm's law remember that voltage and current are directly proportional so if we increase voltage current also increases now let's use the formula discuss and take a look at these three sample equations notice that as we increase the voltage the current also increases resistance and current are inversely proportional to each other if we increase resistance current decreases for example in these three equations we have an increasing resistance with a constant voltage as we increase the resistance the current decreases thus they are inversely proportional all right now let's solve some simple problems let's try calculating for the current find the current of a wire through a resistor of resistance equal to 2 ohms if the voltage of the battery is 9 volts we have the formula current equals voltage divided by resistance the given voltage is 9 volts and resistance of 2 ohms 9 volts divided by 2 ohms equals 4.5 amperes how about we try solving for resistance what is the resistance of an electric flat iron in which the current is 10 amperes when the potential difference is the 220 volts used in our home now we have the formula resistance equals voltage divided by current the given voltage is 220 volts and current of 10 amperes so 220 volts divided by 10 amperes equals 22 ohms all right let's try this last one we will be solving for voltage what voltage will be needed to produce 5 amperes through a 20 ohm coil we have the formula voltage equals current times resistance the given current is 5 amperes times the given resistance of 20 ohms so we need 100 volts to produce 5 amperes in the coil in summary ohm's law states that the electrical current flowing in a circuit is directly proportional to the voltage and inversely proportional to the resistance remember that the ohm's law is only applicable if there is a constant temperature that's all for now up next we will be discussing about series and parallel circuits as well as safety electrical home devices see you on our next video and don't forget to keep your minds busy if you like this video please subscribe to our channel and hit the notification icon for more videos like this

Channel: The Learning Bees

Views: 21,872

Keywords: The Learning Bees, Department of Education, DepEd, MELC-Based, Most Essential Learning Competencies, Science, Grade 8, Ohm's Law, Electricity, Resistance, Current, Voltage, Georg Ohm, What is the Ohm's Law, How to solve for resistance, How to solve for current, How to solve for voltage, Calculate, Problem-solving, MELC, How is current voltage and resistance related to each other

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Length: 8min 31sec (511 seconds)

Published: Wed Nov 18 2020