# Chapter 13 - Current of Electricity

###### Videos

Electric charge is the basis behind all study in electricity. The GCE A Levels requires to understand charge as an electrical property which causes objects to exert forces on one another, and also that charge is quantised, and is always an integer multiple of the elementary charge. This video will discuss these concepts.

This video introduces the concept of electric current. In the GCE A Levels, we will be required to analyse steady currents typically, but also time-varying currents on the rare occasion. This video also shows how to visualise current in terms of the flow of electrons, and also mentions the difference between conventional currents and actual electron flow.

In the GCE A Levels, we have to express the current in terms of the drift velocity of the charge carriers. This video will show how this expression is derived, and will explain how we should think of the drift velocity of charge carriers.

This video discusses the electromotive force and potential difference, including how they should be computed, their relationship, and the slight differences between them. The GCE A Levels would require this knowledge.

There are two main ways to compute resistance in the GCE A Levels. This video will introduce resistance is a ratio of the potential difference and current, but also as a function of the dimensions and properties of a particular component.

In the GCE A Levels, we will be asked to work with the concept of electrical power. This video discusses the various ways of computing electrical power, and also the subtle things that we have to be careful of.

In the GCE A Levels, you will be asked to analyse current-voltage characteristic graphs (or I-V graphs) of various components. This video focuses on how to interpret I-V graphs in general, and also introduces Ohm’s Law, and the I-V graph of ohmic conductors.

In the GCE A Levels, you will be asked to analyse current-voltage characteristic graphs (or I-V graphs) of various components. This video focuses on how semiconductor diodes work and how to interpret the I-V graph of a semiconductor diode.

In the GCE A Levels, you will be asked to analyse current-voltage characteristic graphs (or I-V graphs) of various components. This video focuses on how to interpret the I-V graph of a filament lamp, or metals in general, and we will see that the I-V graph shows that the resistance increases as the potential difference across the filament lamp increases. The video will describe why this happens, including balancing the effects of increased thermal lattice vibrations and increased charge carrier concentrations.

In the GCE A Levels, you will be asked to analyse current-voltage characteristic graphs (or I-V graphs) of various components. This video focuses on how to interpret the I-V graph of an NTC thermistor, or semiconductors in general, and we will see that the I-V graph shows that the resistance increases as the potential difference across the NTC thermistor increases. The video will describe why this happens, including balancing the effects of increased thermal lattice vibrations and increased charge carrier concentrations.

Batteries and power sources all have internal resistance, and the GCE A Levels requires us to recognise this. This video will explain how to deal with this internal resistance, and discuss how it affects the terminal potential difference across the circuit.

One of the most common problems in electrical engineering is deciding between power and efficiency. The GCE A Levels sometimes, requires us to perform analysis on this trade off. This video will explain how to maximise both power, and efficiency, and we will see why it is impossible to have both.