Solutions: As the fuel level drops, the float which stays on the fuel surface will descend. The rod which is attached to the float will turn clockwise about the pivot X. As the rod turns, the resistance on the variable resistor increases. This increases the resistance of the circuit. Hence the current flowing through the circuit will decreases, causing the needle to deflect more to the left, indicating towards E (empty). Thus the reading on the fuel gauge decreases. Solutions: (i) Both the fixed resistor and sensor are in series. Total effective resistance Re = 5000 + 1000 = 6000 ohms V = IR 12 = I x 6000 I = 0.0020 A Hence potential across Y, V = IR (where I is constant in a series circuit) = 0.0020 x 1000 = 2.0 V (ii) When the temperature increases and the resistance of sensor Y decreases, the total effective resistance of the circuit decreases . Current flowing through the circuit increases. Since V = IR, where the R of the fixed resistor is a constant 5000 ohms, as current I increases, the potential difference across the 5000 ohms resistor will increase.

Ticker tape timer is a device which punches dots on a tape at specific time interval. The tape can be attached to a moving object. With information of the frequency of the ticker timer and the spacing of the dots, we are able to analyse the motion of the moving object. View the following videos to understand more about the ticker tape timer and also some typical questions on ticker tape timer. Explanation of Ticker Tape Timer Questions on ticker tape timer

Answer: Option D

A common mistake is to state that the reason for switch to be on the live wire is “so that the switch can turn on/off the appliance”. This explanation is wrong. In general, in the event where the fuse is blown or the switch is open, it disconnect the appliance from the high potential of the live wire. So the appliance will no become ‘live’ and it is save to touch even though there is a fault. Refer to the video for the reason why switch and fuse must be on the live wire. Refer to the notes given

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: