# [S3] Lesson 32 : Light EOY Revision 1 – Reflection + Refraction+ (AM) Trigonometry Equations + Metals III Updates/Debrief

[S3 Physics PMCians]

What we did in 2 hours:

On 6th, 8th and 9th Aug, the S3 PH has come together to complete the following:

1) Secret Enclosed – Light Part I (Reflection and Refraction)

2) The Final Lap – Light Waves 1

Two things to remember:

1. For reflection: The three steps to drawing how the eye perceive the object through the mirror is the usual procedure we adopt to solve questions. Always remember that in order for an eye to see an image clearly, i) the rays from object to eye must not be obstructed, and ii) the point of incidence must be located on the actual mirror.

1. For refraction: TIR  occurs when i) light travels from optically denser to less dense medium, and ii) angle of incidence is bigger than critical angle. Always remember, in PMC, n2 is usually the optically denser medium.

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

In this coming week (Aug 13, 15 and 16), we will continue our revision on Light II – Lens. Do remember to bring along your pencil and ruler for this 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 Equations. From the concept of ASTC and Trigo Graphs, we learnt to solve trigonometric equations. To solve for ALL possible angles, we learnt to manipulate the given domain to what we want.

As we are exploring more question types, we noticed that these equations can involve algebraic factorisation! It gets tougher when we need the negative angles from the annoying domain. Just remember the techniques we did in class! 😉

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

Special Mention:

In the next lesson, we will look at Trigonometry Identities. Yes, more formulae! It’s not as simple as “sine over cosine equals to tangent”. These formulae will be provided in the formula sheet (Thankfully!)

We will use these formulae to solve more complicated trigonometric equations! See you in class!

Your friendly PMC S3 Math tutors

[S3 Chemistry PMCians]

What we did in 2 hours:

We have concluded our chapter on metals and applied the reactivity series for the choice of extracting agent to obtain pure metal from ores and for identifying sacrificial metals (i.e. more reactive metals prefer to be oxidised and will serve as the sacrificial metal).

You may now complete all of your take home package on Metals. Please be reminded to complete your Metals Quick Fire Quiz. Answers will be given to you in the upcoming lesson.

Special Mention:

We are going into our final chapter of our Sec 3 syllabus on Energy Changes and will be going into revision for our SA2. Chemical reactions produce and absorb heat and this property allows chemists to develop useful real life items such as heat pads and self heating hotpots! Here’s a video: