#### How LCD screens work.

How LCD screens work Although the term liquid crystal sounds like an oxy moron, it is in fact describing a solid whose particles are free to move around each other almost like a heavy molecular level. Crystals are either categorised as thermotropic or lyotropic. Thermotropic crystals are affected by changes in temperature and some times pressure. They are either isotropic (with no particular arrangement) or nematic (with a pattern). Ferro electric crystals use nematic crystals with a spiral pattern to allow for microsecond switching. It is necessary to have a layer of glass to maintain a certain pressure and to alow for even quicker switching. There are four facts that allow for liquid crystals to work in the way they do * Light can be polarized. * Liquid crystals can transmit and change polarized light. * The structure of liquid crystals can be changed by electric current. * There are transparent substances that can conduct electricity. Most simple LCD's emit no light of their own, they depend on light reflected back off the rear surface or that of a back light which once again reflects off of the rear panel. There are two main types of LCDs used in computers, passive matrix and active matrix. Passive-matrix LCDs use a simple grid to supply the charge to a particular pixel on the display. Creating the grid is quite a process! It starts with two glass layers

• Word count: 735
• Level: GCSE
• Subject: Maths

#### Tiles investigation

Investigation 'Tiles' A builder is asked to arrange some tiles on a wall in a 4 by 4 array as shown below To help him he has variously shaped 'spacers' which he places between the tiles. He uses the spacers to separate the tiles evenly as in the following arrangement. He has used 4 spacers like this He uses 9 spacers shaped like this He uses 12 spacers shaped like this He has 25 spacers altogether Aim of Investigation: The aim of this investigation is to investigate the number of different types of spacers required for other arrangements of tiles. Result Table 1: Arrangement (A) C S N by 1 4 0 0 2 by 2 4 4 3 by 3 4 4 8 4 by 4 4 9 2 By observing the results from this table after drawing the arrangements, as shown above, I have discovered a formulae using the trial and error method to find out what spacers I need for the different arrangements. Formulae C= 4 S = (A - 1) 2 N = 4(A - 1) I have also discovered that the spacer (S) is increasing in square numbers. I must also state that the letter (A) represents the arrangements. However when this letter is in formulae, you must take the first number of the arrangement in order to work out either (S) or (N). I have discovered that (N) increases by 4 when the arrangements are in order. By using the formulae I am able to find out the following arrangements shown in the table and the diagrams.

• Word count: 879
• Level: GCSE
• Subject: Maths

#### Maths Mayfield High School Data Handling

I have been presented with data of secondary nature, about a school named Mayfield high school. This is table shows the number of pupils. Year group Number of boys Number of girls Total 7 51 31 282 8 45 25 270 9 18 43 261 0 06 94 200 1 84 86 70 There 1183 students in this high school, and they have carried out several surveys, and put information on every single students into their own record on a database. The database contains several kinds of information, for example, name, age, year group, IQ, weight, height, eye colour, hair colour, test results, etc. The variations I have chosen to follow for my coursework are: . The relationship between height and weight Keeping in mind that there are 1183 students, I cannot provide these enquiries onto each pupil. I must take a suitable sample. Sampling helps to pick and choose some data needed to gain a result. Here are the methods available: Year group Total number of students Number students to be taken 7 282 282/1183 x 100 = 24 8 270 270/1183 x 100 = 23 9 261 261/1183 x 100 = 22 0 200 200/1183 x 100 = 17 1 70 70/1183 x 100 = 14 Total students = 100 The students taken must be taken at random. SAMPLE SIZE: Taking a fixed percentage out of the 1183 students uses a sample size. For example 10% is taken from the whole school. You would end up with 118 students. On the other hand a

• Word count: 1731
• Level: GCSE
• Subject: Maths