# Convex lenses – what to do in an exam

There is a lot to remember when it comes to convex lenses. Mammoth Memory recommend that if convex lenses ray diagram questions come up in the physics exam, then before you start you should jot down three quick sketches that will remind you of all that you need to remember (use a ruler to help).

Sketch 1 draw the object at 2F

Sketch 2 draw the object at 1F

Sketch 3 draw nine objects before the lens.

These are the three quick sketches you need to draw in the exam:

 NOTE: 1. Don't forget to put the red arrows on so that you don't forget 7, 8, 9 in the correct order. 2. Put NO in the empty triangle to remind you that nothing is in this.

Please practise these three sketches time and again. Time yourself.

These three quick sketches wiil help you provide accurate and fast answers to any convex lens ray diagram questions.