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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...
Evan Toh
Oct 22, 20241 min read
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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...
Evan Toh
Oct 21, 20241 min read
57 views
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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,...
Evan Toh
Oct 21, 20241 min read
61 views
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2010SPp1q12 Lens - focal length definition
Answer: Option C Focal length f is the distance between the focal point and the centre of the lens (optical centre) . Note that only...
Evan Toh
Jan 1, 20241 min read
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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...
Evan Toh
Dec 31, 20231 min read
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SP N2007 P1 Q16 – Which events will cause the fuse to blow?
An electric cable contains three wires live, neutral and earth. The cable is correctly wired to a plug which contains a 3A fuse. The...
Evan Toh
Dec 31, 20232 min read
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Identifying what lens, focal length and image from 2 rays – PP2010P1Q23 and SP2014P1Q11
These 2 questions are actually the same. Q23 is from 2010 Pure Physics P1 while Q11 is from 2014 Sci Physics P1. Take a look at these 2...
Evan Toh
Dec 31, 20231 min read
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Evan Toh
Dec 31, 20231 min read
6 views
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2013SPp1q17 What is the new P when V across resistor is doubled? Similar 2018PPp1q31
Answer: Option C View the videos below to learn how to solve it. There are more than one method. Alternatively, you may put values to...
Evan Toh
Dec 31, 20231 min read
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N2007P1Q9 Pure Physics – Energy needed to pump water up a building
Answer: Option B Since water will naturally reach 40m high from the bottom of the apartment, you only need to pump the water up by a...
Evan Toh
Nov 30, 20231 min read
11 views
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2004PPp1q4 2010SPp1q4 Dynamics (3rd law)
Answer: Option D Key concept here is Newton’s 3rd Law. Action equals reaction. Both trolleys are connected by the spring, hence the...
Evan Toh
Nov 30, 20231 min read
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