Question 1Warm-upFoundation
A drawing of a cell is 20 mm long. The real cell is 0.5 mm long. What is the magnification?
Image ÷ real.
Worked solution
- , so
Answer:
GCSE & IGCSE biology practice
Magnification questions and answers
Magnification tells you how many times bigger the image is than the real object: magnification . Both sizes must be in the same unit. 1 mm = 1000 µm (micrometres). The questions include microscopes, micrographs and scale bars.
8 questions · Foundation tier · Every answer is checked as you type it, with a full worked solution. Updated .
Where magnification comes up
| GCSE (AQA) | Biology and Combined Science, Foundation and Higher: calculate magnification, real size and image size using magnification = image size ÷ real size. |
|---|---|
| Cambridge IGCSE (0610) | Core: state and use magnification = image size ÷ actual size, using millimetres. Supplement (Extended): convert between millimetres and micrometres. |
The method
- Put both sizes in the same unit first (1 mm = 1000 µm).
- Magnification = image size ÷ real size.
- Real size = image size ÷ magnification; image size = real size × magnification.
- Total magnification of a light microscope = eyepiece × objective.
Magnification questions
Try each one before looking at the hint. If you're stuck, the AI tutor can talk you through it step by step.
Warm-up
Question 2Warm-upFoundation
A light microscope has a ×10 eyepiece and a ×40 objective lens. What is the total magnification?
Multiply them.
Worked solution
Answer:
Exam-style
Question 3Exam-styleFoundation
An image is 8 mm long at a magnification of ×400. What is the real length in mm?
Real size = image ÷ magnification.
Worked solution
- mm
Answer: mm
Question 4Exam-styleFoundation
A specimen is 0.1 mm long. It is viewed at ×250. How long is the image?
Image = real × magnification.
Worked solution
- mm
Answer: mm
Question 5Exam-styleFoundation
Convert 0.02 mm into micrometres (µm).
× 1000.
Worked solution
- µm
Answer: µm
Question 6Exam-styleFoundation
A cell is 50 µm wide. In a photograph it is 25 mm wide. What is the magnification?
Convert 25 mm to µm first.
Worked solution
- mm µm
Answer:
Challenge
Question 7ChallengeFoundation
In an electron micrograph at ×15 000, a mitochondrion is 30 mm long. What is its real length in µm?
Real size in mm, then convert.
Worked solution
- mm
- µm
Answer: µm
Question 8ChallengeFoundation
A scale bar on a micrograph is 10 mm long and labelled 50 µm. What is the magnification?
The scale bar's image size is 10 mm; its real size is 50 µm.
Worked solution
- mm µm
Answer:
Common mistakes
- Mixing mm and µm in the same calculation.
- Dividing the real size by the image size.
- Giving a magnification a unit (it has none).
Stuck on one of these?
The TutorAura AI tutor works through it with you step by step, with the reason for each step, then gives you one like it to try. It checks your working too.
Try the AI tutor freeMore biology questions
Sources
The questions are our own. The “where it comes up” notes are from each board's published specification, checked on 27 October 2026:
Practise biology with your own AI tutor
Questions at your level, help when you're stuck, and a plan for your exams. Free for 3 days, no card needed.