Evan Toh
Different Converging Lens Ray Diagram questions
Drawing ray diagrams for converging lens come in many forms. But the basic concepts needed are the 3 rays (which have rules to follow) to...
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Evan Toh
Oct 221 min read
2010SPP2Q12 Fuel gauge using variable resistor
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...
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Evan Toh
Oct 211 min read
Using P = I^2R and P = V^2/R to explain which component uses the highest power or energy.
Instead of P = IV to explain, it might be easier to explain using P = I^2R when the components are connected in series where current I is...
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Evan Toh
Oct 211 min read
When a thermistor is connected in series with a fixed resistor, how to explain the p.d. varies as resistance temperature changes?
When two components are connected in series, where one is a fixed resistor and the resistance of the other can vary (e.g. thermistor,...
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Evan Toh
Oct 151 min read
2012PPp2q07 - Find the p.d. across A and C
Instead of the usual finding of potential difference across a component, in this question, you are required to find the p.d. across two...
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Evan Toh
Sep 301 min read
Lens – Complete the rays S and T as they pass through the lens
To do similar questions, it is important to know the 3 rays which have rules to follow in order to locate the image. Look through the...
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Evan Toh
Jan 311 min read
2021SPp2q8 - Which appliance uses most energy (using P = V^2/R to explain)
Resistors may be connected in series or parallel. When asked which resistor has higher power (hence higher energy), in general we will...
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Evan Toh
Jan 311 min read
PP2017Q11 Using P=I^2R and P=V^2/R to explain which has higher power
Resistors may be connected in series or parallel. When asked which resistor has higher power (hence higher energy), in general we will...
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Evan Toh
Dec 31, 20231 min read
Total Internal Reflection (TIR) example 01
Solutions: a) Refraction b) 48.6o c) c = 41.8o e) 70o d) Total internal reflection has occured, as the angle of incidence is...
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Evan Toh
Dec 31, 20232 min read
2013SPp2q9 – Pressure and Moment
Solutions: (a) (i) A bigger force than F can be obtained due to the lever system and hydraulic system . Lever system: Applying...
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Evan Toh
Dec 31, 20231 min read
Which is better to cool the food? Copper or ice at 0oC - 2008SPP2Q6(b)
Other examples in our daily lives: In some supermarket, the seafood are placed outside of air-conditioned place. The seafood is kept cold...
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Evan Toh
Dec 31, 20231 min read
PP2008Q11OR Thermistor in series with fixed resistor, explanation on pd and graph
As both the fixed resistor and the thermistor are connected in series, the sum of potential difference across them will be equal to the...
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Evan Toh
Dec 31, 20231 min read
When to use the concept PV = constant and P1V1 = P2V2 to solve?
When temperature is constant (for o-level), when a fixed mass of gas (fixed number of air molecules) is compressed in a closed system...
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Evan Toh
Dec 31, 20231 min read
Total Internal Reflection (TIR) example 02
Solutions: a) 38.8o b) 41.8o c) 51.2o . The ray does not emerge as total internal reflection has occurred. The angle of incidence is...
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Evan Toh
Dec 31, 20231 min read
2017PurePhyP2Q5 Two points on the rope wave with displacement-time graphs given
In this this question, the displacement-time graphs are given, which are different from displacement-distance graphs. In the...
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Evan Toh
Dec 31, 20231 min read
Using barometer to estimate height of mountain
At sea-level, the barometer which Pie is holding reads 760 mm of Hg. When he is at the top of Mount Pie, the same barometer reads 230 mm...
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Evan Toh
Dec 1, 20231 min read
Boy on spring board - Moments Question using Simultaneous Equations
Note: Non-uniform plank means the CG of the plank is not at its centre a) Find the weight of the boy. b) How far is the centre of gravity...
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Evan Toh
Nov 30, 20231 min read
Car A and Car B – Find the time one overtakes the other
The speed-time graph of Car A and Car B, along a straight road over 4 seconds is shown below. a) Calculate the acceleration of Car A and...
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Evan Toh
Nov 30, 20231 min read
Modification to ammeter to measure bigger current
Sensitivity of the ammeter means that how small a current the ammeter can measure. Example, if the original set up is 0.2 A per division,...
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