Physics Isa
Introduction
I have chosen to investigate a factor that affects the output of a potential divider circuit. A potential divider is resistors connected in series across a voltage source; used to obtain a desired fraction of the voltage. A resistor is a device having resistance to the passage of an electric current which affects the output voltage (Vout). The factors that I could investigate are changing the resistance of r2 and record the output (Vout), or use a light-dependent resistor (LDR) and change the resistance of r2 and record the output (Vout).
Theories
Resistors restrict or limit the flow of current in a circuit. The ability of a material or component to resist current flow is measured in ohms. There are three main types of resistor: * Fixed resistors - are the most common type of resistor. They have three important uses: protecting components, dividing voltage between different parts of a circuit, and controlling a time delay. * Variable resistors (or potentiometers) - There are two types of variable resistor: Variable resistors, which are altered continually as they work: e.g. for volume control in a radio, and pre-set potentiometers, which have a resistance control that is adjusted and then fixed. These resistors would normally be adjusted once only. * Special resistors, such as thermistors and light-dependent resistors (LDRs): Thermistors change resistance as temperatures change. Most thermistors have a negative temperature coefficient, meaning their resistance falls as temperature increases. Thermistors are used in temperature-sensing circuits. Light-dependent resistors (LDRs) change resistance as light levels change. The light levels are detected by a photo-sensitive plate on the resistor. Most LDRs have a negative light coefficient, meaning that their resistance falls as the amount of light falling on them increases. LDRs are used in light-detection circuits.
Potential divider circuit
In a potential divider, a fixed resistor is used to
I have chosen to investigate a factor that affects the output of a potential divider circuit. A potential divider is resistors connected in series across a voltage source; used to obtain a desired fraction of the voltage. A resistor is a device having resistance to the passage of an electric current which affects the output voltage (Vout). The factors that I could investigate are changing the resistance of r2 and record the output (Vout), or use a light-dependent resistor (LDR) and change the resistance of r2 and record the output (Vout).
Theories
Resistors restrict or limit the flow of current in a circuit. The ability of a material or component to resist current flow is measured in ohms. There are three main types of resistor: * Fixed resistors - are the most common type of resistor. They have three important uses: protecting components, dividing voltage between different parts of a circuit, and controlling a time delay. * Variable resistors (or potentiometers) - There are two types of variable resistor: Variable resistors, which are altered continually as they work: e.g. for volume control in a radio, and pre-set potentiometers, which have a resistance control that is adjusted and then fixed. These resistors would normally be adjusted once only. * Special resistors, such as thermistors and light-dependent resistors (LDRs): Thermistors change resistance as temperatures change. Most thermistors have a negative temperature coefficient, meaning their resistance falls as temperature increases. Thermistors are used in temperature-sensing circuits. Light-dependent resistors (LDRs) change resistance as light levels change. The light levels are detected by a photo-sensitive plate on the resistor. Most LDRs have a negative light coefficient, meaning that their resistance falls as the amount of light falling on them increases. LDRs are used in light-detection circuits.
Potential divider circuit
In a potential divider, a fixed resistor is used to