Electric Current

The next few slides are not on your note They are just interesting

Electric Fish, Eels, and Rays For humans, we know that water and electricity are not good to mix For some animals, this safety concern about electricity is not a problem. In fact, they survive because they can use electricity in the water

Electric Fish, Eels, and Rays The elephantnose fish from central Africa has an extended nose that contains about 500 electric sensors These sensors are used to help this tiny fish find food. The electric sensors help it find smaller living things crawling along the bottom of the river or swimming in the water. Research has shown that these electric sensors are so sensitive that they can detect chemical pollutants

Electric Fish, Eels, and Rays The electric eel in lives in the murky waterways of the Amazon and Orinoco river basins of South America. The eel’s electricity comes from a special organ in its long tail that contains thousands of muscle cells that work like tiny batteries. Each cell can produce only a small amount of electricity, but by working together all the cells can produce controlled bursts of electricity equal to five times the energy of a standard wall socket.

Electric Fish, Eels, and Rays These electrical bursts are used to stun prey when the electric eel is hunting for food. Some electric eels also generate an electric signal to attract a mate.

Electric Fish, Eels, and Rays The Pacific electric ray, found along the west coast of North America, has an electric organ located in its head. This organ can generate enough electricity to knock down a human. Other types of electric rays use these electric shocks for defence when they are attacked.

This is part of the Note Electric Current is the measure of the rate of electron flow past a given point in a circuit; measured in amperes (A).

Think of it in terms of a waterfall Think of it in terms of a waterfall. If you could count the number of water molecules that drop over the edge every second, you could get the rate at which water is flowing past a particular point. Now think of the water molecules as electrons in a wire running past a particular point in a specific amount of time and you have the concept of current.

Measuring Current Current in a circuit is measured using an ammeter. The unit of electric current is the ampere (A). An ampere is a measure of the amount of charge moving past a point in the circuit every second.

One ampere of charge in a circuit means that 6 One ampere of charge in a circuit means that 6.2 x 1018 electrons pass a particular point every second.

When you connect an ammeter or voltmeter to a circuit, they must be on the right terminals. -There are two terminals on a meter that you use to connect to a circuit. The negative (–) terminal is often black, The positive (+) terminal is often red.

Always connect the positive terminal of the meter to the positive terminal of the electrical source. Connect the negative terminal of the meter to the negative terminal of the electrical source.

Human Response to Electric Shock The electric potentials created in the body for muscle movement are around 0.08V. The stronger the current is, the more the muscles contract. If the current is large enough, the part of the body in which the current is flowing will contract and remain contracted until the current ceases.

Human Response to Electric Shock Most people do not feel anything below 0.001 A. at 0.002 A tingling is felt. When the current reaches 0.016 A muscles will contract or convulse. If this current were to pass through the chest it could paralyze the breathing muscles. If a current of 0.05 A passes through the chest for a few seconds, the heart will stop pumping. Electric current above 0.2 amps causes severe burns.

Human Response to Electric Shock https://www.youtube.com/watch?v=o-3s8_a1-fc

Lab 13.5 and 13.6 Page 514 and 516 Only do the current part today