# [S3] Lesson 33 : Light EOY Revision 2 – Thin Lens + (AM) Trigonometry Identities + Energy Changes I Updates/Debrief

[S3 Physics PMCians]

What we did in 2 hours:

On 13th, 15th and 16th Aug, the S3 PH has come together to complete the following:

1) Secret Enclosed – Light Part II (Thin Lens)

2) The Final Lap – Light Waves 2

Do remember:

1. When an object is placed at 2F, the image will be same size. As we move the object nearer to the lens, the image will go further from the lens and become magnified, while moving the object further away from the lens will lead to the image coming nearer to the lens and becoming more diminished.

1. If the light rays from object are parallel before reaching the lens, this means the object is at infinity. The image will be formed on the focal plane of the lens.

1. When the object comes before the 1st F, the image will be on the same size as object. It will also be virtual, upright and magnified. It will be good to remember how to draw the ray diagram for this setup as you already saw from our Final Lap that this is a very commonly asked question.

In this coming week (Aug 20, 22 and 23), we will start our revision with Thermal Part I – Thermal Calculations, Temperature.

Do remember to always bring your Secret Enclosed AND the revision books for all lessons.

Do bring along your calculator for the lesson.

Special Mention:

Should you need assistance in your daily practices in Physics, do send your attempted workings and questions to 9100 1235. We will strive to clarify your doubts.

From the S3PH Team

(Mr Shane, Dr Li and Mr Gary)

[S3 Maths PMCians]

What we did in 2 hours:

This week, we covered on Trigonometry Identities. We learnt some formulae to connect the relationship for trigo2. It is important to be familiar with these formulae as it helps us simplify more complicated trigonometric equations and to solve some proving questions.

As we are exploring more question types, we noticed that these questions can involve algebraic factorisation and special identities!
It gets tougher when we need to consider a list of possible trigo-identity conversions.
Play around with the trigo formulae more frequently and you will be fine.

Please try the Takeaway Questions (Trigonometry Identities) as homework before referring to the solutions.

Special Mention:

In the next lesson, we will be revising the chapters to prepare for year-end exam.

ONSITE students: Please remember to bring the two books for the coming lesson,

(1)    Secret Enclosed Book

(2)    Book 4: The Final Lap Series

ONLINE students: If you have not received the two books, please make arrangement to collect them before attending the lesson.

See you in class!

Your friendly PMC S3 Math tutors

[S3 Chemistry PMCians]

What we did in 2 hours:

We have started on our last chapter before the SA2 exams on Energy Changes and observed how heat is taken in for bond breaking and released upon bond formation during a chemical reaction. We were also introduced to how the difference in heat absorbed or released during these processes result in an exo/endothermic reaction (i.e. exo = energy absorbed < energy released and vice versa).

You should complete your Quick Fire quiz on Metals which was given out the week before and hand it in to me this week to be marked (for on-site students).

Special Mention:

Did you know that dissolving of ammonium salts are endothermic reactions (might be tested!)? Here’s a video: