# The water on earth conducts electricity

## Understand physics 3, textbook

88 2  Workbook page 48 Electric current as a source of danger 1. What are the dangers of current flowing through the body? The human being as a conductor (Fig. 88.1) E1, E4 Set up the experiment according to the sketch. Let the current of a 9 V battery flow through your body and measure the amperage. Do you feel something How does the strength of the current change when the hands are wet? You don't feel anything, because a voltage of 9V never allows so much current to flow through your body that there is danger. In the low voltage range ( page 69), the electrons cannot penetrate the skin well. However, damp skin conducts better than dry skin. This allows stronger current to flow through you. In the bathroom or in the kitchen (Fig. 88.2) E1, E4 Reach a little at first, then deeper into the water! Compare the currents! The current increases as you reach deeper into the water. The current path has a larger cross-section, as a result of which the resistance decreases and the current strength increases. Therefore, never use electrical devices such as a hair dryer when you are sitting in the bathtub (Fig. 88.3)! If a current of around 50mA or more flows through your body, it can damage vital organs via the well-conducting blood and nerve tracts and lead to death. Higher currents cause body tissue burns. Since the household voltage is 230V and high currents can be delivered, it is important to be careful with household electrical appliances. 2. What do you have to pay attention to with sockets? In Fig. 88.4 you can see an open socket. The brown (or black) cable is live and is called the outer conductor (phase conductor). The blue neutral conductor (neutral conductor) and the green-yellow protective conductor (earthing  Page 89) are not live. There is an alternating voltage of 230V between the outer conductor and the neutral conductor (or earth). Never touch the cable of an open socket! The neutral conductor could also be live! V1 eg radiator milliampeter 9V 88.1 humans as current conductor V2 10 V ~ milliammeter for alternating current bare wire power supply water 88.2 in the bathroom or in the kitchen DANGER TO LIFE! 88.3 Blow-drying in water is life-threatening! If electrical currents from around 50V and 50mA flow through the body, there is danger to life due to organ damage. M There is a risk of death when touching • outer conductor and neutral conductor, • outer conductor and earth or a metal object connected to earth (eg housing or water pipe). M Live outer conductor Protective conductor Neutral conductor 88.4 Open socket bare metal (eg screwdriver, nails) DANGER TO LIFE! 88.5 When both sockets of the socket are touched, current flows through the heart. 230 V water pipe outer conductor DANGER TO LIFE! 88.6 Current flows through the body and the aqueduct into the earth. RISK OF DEATH! 88.7 Current flows from the outer conductor through the body to earth. For testing purposes only - property of the publisher öbv