Science assignment 1. Draw an energy chain to show energy transforms in an eclectic kettle.
Electrical potential energy – electrical energy - heat energy – kinetic energy – sound energy – elastic energy.
2. Explain how an electric current provides energy for electric appliances.
Electric lights, refrigerators, TV and stereos need a steady source of electric energy comes from an electric current, which is the flow change through a conductor. In solids, the flowing charges are electrons. In liquids, the flowing charges are ions, which can be positively or negatively charge.
When electric charges move in a wire, we say that an electric current flows in the wire. It's like the way a current of water flows in a river.
For an electric current to flow, we need two things:
• Something to make the electricity flow, such as a battery or power pack
• A complete path for the current to flow in. This is called an electric circuit.
An electric current will not flow if we do not have a power source (a cell, battery or power pack). It also won't flow if the circuit is not complete. One end of the power source must be joined to the other end by the wires and components of the circuit.
3. Describe the relationship between current power and electrical energy used by electric appliances
An electrical circuit is simply an energy transformation tool.
Energy is provided to the circuit by an electrochemical cell, battery, generator or other electrical energy source. And energy is delivered by the circuit to the load at the location of the load.
The rate at which this energy transformation occurs is of great importance to those who design electrical circuits for useful functions.
Power - the rate at which mechanical work is done - Power is the rate at which electrical energy is supplied to a circuit or consumed by a load. The electrical energy is supplied to the load by an energy source such as an electrochemical cell. A cell does work upon a charge to move it from the low energy to the high energy terminal. The work done on the charge is equivalent to the electrical potential energy change of the charge. Thus, electrical power, like mechanical power, is the rate at which work is done. Like current, power is a rate quantity. Its mathematical formula is expressed on a per time basis.
4. Describe the relationship between resistance and current as show by Ohms law.
The current and resistance are inversely proportional to each other.
Here is how the two are related in a series circuit:
Current = Voltage / Resistance
Resistance = Voltage / Current
The amount of current flow in a series circuit can be changed by changing the ohmic value of resistance in the circuit but the ohmic value of the resistance in a given circuit is fixed and cannot be changed by merrily changing the amount of current flow.
Ohm's Law: V = IR
The connection between voltage and resistance can be more complicated in some materials. These materials are called non-ohmic. We'll focus mainly on ohmic
