IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: rascalrahul on November 03, 2009, 03:05:00 am

Title: AS Biology practical help
Post by: rascalrahul on November 03, 2009, 03:05:00 am

Can someone please explain to me, in fair detail, the difference between an eye-piece graticule and a stage micrometer? Where are they (on slide? on microscope?)? And what are the units/divisions of each one?

Doing the bio prac in 2 days and need help

Title: Re: AS Biology practical help
Post by: Light on November 03, 2009, 07:43:47 am

An eyepiece graticule is the scale found on your miroscope in eyepiece and can be rotated to measure any directions you like.Stage micrometer is a scale on slide which helps you calibrate and determine how long is 1 division on eyepiece graticule. The division of stage mirometer and eyepiece graticule is usually 100 units.this is what u do:1)measure stage micrometer using ruler
                                                                                               2)find length of 1 divisions on stage micrometer
                                                                                               3)view it under microscope and see how many divisions of 1 unit of
                                                                                                   stage micrometer covers
                                                                                               4) u measure the required cell with eyepiece graticule
beware:the length of each division of eyepiece graticule  changes according to magnification.dont assume it is the same all time.