# Unit 1: Electricity

HideShow resource information

- Created by: Karlw1lk1ns
- Created on: 10-12-14 10:49

View mindmap

- Unit 1: Electricity
- Current, Amps (I)=Q/T
- Current is rate of flow of charge
- Measured using an Ammeter in series

- Current is rate of flow of charge
- Potential Difference, Volts (V)= W/Q
- Measured using a Voltmeter in Parallel
- Work Done (Joules) per unit charge (Coulomb) to move charge through a resistor.

- Resistance,Ohms (R) =V/I
- Resistance is a measure of difficulty in the flow of current in a circuit or component
- Ohms Law: As long as temperature is constant; the current through a Ohmic conductor is directly proportional to the potential difference across it
- I/V Charactistics; On a graph a curve shows R is changing and not constant. If the gradient is SHALLOWER then the RESISTANCE IS HIGHER
- Metallic Conductors (Most) are Ohmic therefore have a straight graph
- Filament Lamp has a curve, the metal wire heats up causing more resistance
- Semiconductors; are used in sensors
- Thermistors; different types. Such as (NTC) Negative Temperature Coefficient
- Light Dependent Resistors
- More energy releases, more charge carriers

- Resistivity (?) ?m= (R*A)/L [Resistance x Surface Area (M^2)]/Current
- Superconductors have little/no resistance. This can be forced by cooling a material below its transition temperature
- Can make strong electromagnets that don't need constant power source

- Superconductors have little/no resistance. This can be forced by cooling a material below its transition temperature
- Power, Watts (P)=IV
- Resistance,Ohms (R) =V/I
- Resistance is a measure of difficulty in the flow of current in a circuit or component
- Ohms Law: As long as temperature is constant; the current through a Ohmic conductor is directly proportional to the potential difference across it
- I/V Charactistics; On a graph a curve shows R is changing and not constant. If the gradient is SHALLOWER then the RESISTANCE IS HIGHER
- Metallic Conductors (Most) are Ohmic therefore have a straight graph
- Filament Lamp has a curve, the metal wire heats up causing more resistance
- Semiconductors; are used in sensors
- Thermistors; different types. Such as (NTC) Negative Temperature Coefficient
- Light Dependent Resistors
- More energy releases, more charge carriers

- By combining Power and Resistance you can say that:
- P=I^2*R
- P=V^2/R

- 1 Watt =1 Joule / Second
- Energy, Joules (J)= P x t
- E=V*I*t
- E=(V^2/R)*t
- E=I^2*R*t

- Energy, Joules (J)= P x t

- Resistance,Ohms (R) =V/I
- Energy, Joules (J)= P x t
- E=V*I*t
- E=(V^2/R)*t
- E=I^2*R*t

- EMF and Internal R
- ?= V+v
- ?=IR+ir
- V = ? - v
- V= ? - Ir
- Low IR is great for batteries as less energy is lost. For safety high voltage power supplies have high IR so a short allows only a small current to flow
- Terminal PD is the EMF - lost volts
- V = ? - v

- Current, Amps (I)=Q/T

## Comments

No comments have yet been made