The majority of mobile phones use touch screens. Three common technologies are used by different mobile phone manufacturers. Choose one of the following mobile phone technologies: • resistive • capacitive • infrared Chosen technology

Mark scheme

Marking points from the official mark scheme (May/June 2015). The mark or mark type is shown in brackets.

1. [2] (i) Either of the three options, resistive, capacitive or infra-red must be chosen maximum of two marks from chosen technology: resistive – uses multiple layers of material ... – that transmit electric currents – when the top layer/screen is pushed/touched into the lower/bottom layer ... – the electric current changes and location of “touch” is found capacitive – current sent/flows out from all 4 corners of the screen – when finger/stylus touches screen, the current changes – the location of "touch" is calculated infra-red – an "invisible" grid on the screen (pattern of infra-red LED beams) – sensors detect where the screen has been touched through a break in an infrared beam(s) – the position where the screen touched is calculated
2. [2] (ii) 1 mark for benefit, 1 mark for drawback Resistive benefits: – inexpensive/cheap to manufacture – can use stylus/finger/gloved finger/pen drawbacks: – poor visibility in sunlight – vulnerable to scratching – wears through time – does not allow multi-touch facility capacitive benefits: – good visibility in sunlight – (very) durable surface – allows multi-touch facility drawbacks: – screen (glass) will shatter/break/crack (on impact) – cannot use when wearing (standard) gloves infra-red benefits: – good durability – allows multi-touch facility – can use stylus/finger/gloved finger/pen drawbacks: – expensive to manufacture – screen (glass) will shatter/break/crack (on impact) – sensitive to dust/dirt