The ‘D.C.’ here mean direct current . It means that the current flows in one direction in the circuit . The direction of the direct current refers to the conventional current , and it flows out of the positive (+) terminal of the cell / battery, around the circuit and flows back into the negative (-) terminal . [Note: the direction of the electron flow is opposite to the conventional current] To understand DC circuit, it will be useful to relate to a river system. Refer to the 3 videos below to learn more about 01: DC circuit similar to river system, 02: Series Circuit 03: Parallel Circuit and 04: Combined Circuit. 01: How is DC circuit related to a river system 02: Series Circuit 03: Parallel Circuit 04: Combined Circuit (Series and Parallel) Now, after you have the basic concepts and rules for the circuits, let’s look at some simple example to reinforce you understanding. Example 01: Series Circuit Example 02: Parallel Circuit Example 03: Combined Circuit Example 04: PP2012P2Q7 DC circuit : pd across 2 points on two separate branches.

For resistors connected in series, the total resistance is the sum of all resistance. Re = R1 + R2 + R3 For resistors in parallel, the total resistance is Re = (1/R1 + 1/R2 + 1/R3)-1 or 1/Re = 1/R1 + 1/R2 + 1/R3 Refer to the video to learn how to find total effective resistance of the circuits.

Overview of Total Internal Reflection (TIR) Explanation of the various stages:

Wavefront is an imaginary line which joins all identical adjacent points (e.g. crests) in phase . Note that the distance between two successive wavefronts is the wavelength . Wavefront can be created in a ripple tank. The video below shows how horizontal wavefront is created. The video below shows how other types of wavefronts are produced

Page 4 of Work Energy and Power: Understanding COE

Refer to the video tutorial for the basic concepts of hydraulic system. The notes are attached below. Understanding Hydraulic System 01 Understanding Hydraulic System + Lever 02 Notes:

Answer: Option D

Refer to this MCQ from PurePhysics 2015P1Q6 Answer: Option C

(1) (2) (3) (4)

Vector diagram is commonly referred to parallelogram diagram . Vector diagrams are generally divded into 3 categories: 1) 2 forces acting on a body, there is a resultant force. (Newton’s 2nd Law) 2) 3 forces acting on a body, the body is at rest / in equilibrium or moving at constant speed . (Newton’s 1st Law, Net force = 0N)  – The resultant force due to any 2 forces is equal and opposite to the 3rd unknown force. 3) 3 forces acting on a body, the body is at rest / in equilibrium or moving at constant speed (Newton’s 1st Law, Net force = 0N)    – Only 1 known force, angles given, using closed loop triangle to find the 2 unknown forces. Let’s look at some examples for each category. 1) 2 forces acting on a body, there is a resultant force. (Newton’s 2nd Law) 2) 3 forces acting on a body, the body is  at rest / in equilibrium  or moving at  constant speed . (Newton’s 1st Law, Net force = 0N) – The resultant force due to any 2 forces is equal and opposite to the 3rd unknown force. – You can either use  parallelogram rule  or  closed looped triangle . Example 1: Body at rest – Using Parallelogram Rule Example 1: Body at rest – Using Closed-Looped Triangle Example 2: Body at constant speed – Using Parallelogram Rule Example 2: Body at constant speed – Using Closed-Looped Triangle 3) 3 forces acting on a body, the body is  at rest / in equilibrium  or moving at  constant speed  (Newton’s 1st Law, Net force = 0N)     – Only 1 known force, angles given, using closed loop triangle to find the 2 unknown forces. Example 1 Example 2

For Combined Science (Physics), drawing of vector diagram is a must.In general, two known forces are given and the resultant force of these two forces is to be found using the vector diagram . There are two methods to draw vector diagram 1) Parallelogram method and 2) Tip-to-tail method.  In this post, the parallelogram method is used.

On the nuclear trail: The dawn of a global renaissance in nuclear energy (Source: Strait Times 19 Oct 2024) https://www.straitstimes.com/multimedia/graphics/2024/10/nuclear-energy-global-renaissance/index.html?shell Image source: ChatGPT