Current Electricity Lesson 1 Basics of Electric Current

Current Electricity Lesson 1: Basics of Electric Current NOTE: I will be plugging grades now, if you have tasks not turned in including projects, please turn them in ASAP before the end of the Second Period today. Those who have finished all tasks can move on to today’s tasks. Those who cannot complete today’s work today, can turn it in on Friday, which is IF day. You can take my help during my office hours.

CURRENT ELECTRICITY We studied Static Electricity in detail. Static Electricity is all about creation and/or transfer of charges from one body to the other by Friction, Contact, or Induction. After the charges have been created, they get simply stored in the object. That is why it is called Static – remaining in its location. Current means flow with force and direction through a distance and through a medium. Think of Ocean Currents and Air Currents. Current Electricity deals with the flow of electrical charges from one place to other, with force and direction and such a flow occurs through a circuit. What is a circuit? A circuit is a wired loop, through which electrical charges from a source of electric power can be allowed to pass through and they can be measured and tapped. Tapping the electric charges is done by having a switch and the object, you want electricity to flow in, for example, a light bulb, an electric iron box, an electric stove, etc. For the measurement purposes, we can measuring devices in the circuit; such measuring devices are: Ammeter – to measure the current Voltmeter – to measure the potential difference or voltage Ohm meter – to measure the resistance In modern times, the Multimeter serves as a single device to measure all the three. You have to change the mode, that is it. A simple electric circuit is shown here: You notice that Resistor is an integral part of an electric circuit. Why do we need a resistor? We need Resistor to regulate the amount of electricity we want to operate the intended object or gadget. For example, you need a small amount of electric current to glow a bulb; but without regulating the amount, if you are going send all the electric current from the source, the bulb will blow up. Imagine the flow of electricity as the flow of water. If you want to reduce the force of flowing water, then you need to place obstacles on its way. So, a resistor is like an obstacle o the path of the electricity. Resistors introduce resistance in the circuit. Resistors are commercially available, and they come in different values of ohm (recall – ohm is the unit for the measurement of resistance.

1. The Volt The pressure that is put on free electrons that causes them to flow is known as electromotive force (EMF). The volt is the unit of pressure, i. e. , the volt is the amount of electromotive force required to push a current of one ampere through a conductor with a resistance of one ohm. 2. The Ampere The ampere defines the flow rate of electric current. For instance, when one coulomb (or 6 x 10 18 electrons) flows past a given point on a conductor in one second, it is defined as a current of one ampere. 3. The Ohm The ohm is the unit of resistance in a conductor. Three things determine the amount of resistance in a conductor: its size, its material, e. g. , copper or aluminum, and its temperature. A conductor’s resistance increases as its length increases or diameter decreases. The more conductive the materials used, the lower the conductor resistance becomes. Conversely, a rise in temperature will generally increase resistance in a conductor. Ohm’s Law defines the correlation between electric current (I), voltage (V), and resistance (R) in a conductor. Ohm’s Law can be expressed as: V = I × R Where: V = volts, I = amps, R = ohms Ampacity is the amount of current a conductor can handle before its temperature exceeds accepted limits. These limits are given in the National Electrical Code (NEC), the Canadian

Ohm’s Law Problem Solving Ohm’s law can be represented by the triangle given and the three equations are based on Ohm’s Law A set of problems and their solutions are given for your reference: Answer Key http: //ibhandari. weebly. com/uploads/2/6/5/6/26565527/ ohms_law_worksheetkey. pdf YOUR TASK 1: Complete the Quiz at https: //sciencesource 2. pearsoncanada. ca/resources/hotp otato_quiz_09_11_3. htm Send me your score and complete solution for each problem Task 2 is on Next slide

YOUR TASK 2: Take Quiz on Socrative: RENU 2 RAJAS