# AS Biology- Magnification watch

1. Hey, I'm currently struggling on how to work with eyepiece graticule division with these two questions.

B) A slide micrometer, where 1 division equals 10 micrometres was used to calibrate an eyepiece micrometer. At a magnification of x400 it was found that 100 eyepiece divisions measured 16 slide micrometer divisions. What is the size of one eyepiece division in micrometres at this magnification?

C) A blood smear was examined at the same magnification, and the diameter of a neutrophil was found to measure 10 eyepiece divisions. What is the diameter of the neutrophil in micrometres?

Could someone explain how I would work these out please?
2. Sure! :-)

B) You can ignore the magnification completely, since it remains the same throughout.
In a slide micrometer, each division is 10 micrometres.
In the eyepiece, 100 divisions is equal to 16 micrometer divisions.
So essentially 100 eyepiece divisions is equal to 16 multiplied by 10 micrometres. 16*10=160 micrometres. 100 eyepiece divisions is equal to 160µm. Therefore, because there are 100 eyepiece divisions here, 1 eyepiece division is equal to 160/100 micrometres. 160/100=1.6. 1 eyepiece division=1.6µm.

C) You can simply multiply the measurement for one eyepiece division (
1.6µm) by the number of divisions given. There are 10, so 1.6*10=16. The neutrophil is 16µm in diameter.

I hope I helped! (And I hope I did all of that correctly!)

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 17, 2013
Today on TSR

### TSR Pub Quiz 2018 - Anime

The first of our week-long series of entertainment quizzes

### University open days

Wed, 21 Nov '18
• Buckinghamshire New University
Wed, 21 Nov '18
• Heriot-Watt University