Answer: Option A

Take note that the question is looking for specific latent heat of vaporisation during boiling. Hence information of mass m1 before heating is not relevant. There is no change of state of the water, it is merely the heating of the water (which involves specific heat capacity of water). Solutions: Option D Refer to the worked solution below .

These two 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 questions. If you are not sure, view the video below for the explanation. Answer to Q23: Option A Answer to Q11: Option D If you do not know how to answer these 2 questions, view this video and also refer to the lens summary below.

Solutions: Option B Without the current in the river, the time taken for the swimmer to reach Q is 50s. This is based on the vertical constant speed of 1.2 m/s and veritcal (width of river) distance. With the current, which is constant 1.0 m/s, the swimmer will be drifted downstream. But the time taken to reach R from P is still 50s. So with the same 50s, you can calculate the horizontal distance based on the horizontal current speed of 1.0 m/s.

Solutions: Option B Key concepts: Both balls are free-falling, hence both will experience the same acceleration due to gravity 10 m/s2.

Solutions: Option B As lamp X is thicker and shorter , these two factors make the resistance of X lower than Y . Recall: Length increases, R increases & cross-sectional area increases, R decreases. [R = pL/A] As both bulbs are connected to the same mains, (assume 240V), the potential difference across the bulbs are 240 V. Brightness of the bulb depends on power , P = IV or V2/R, since V is constant, I across X is higher due to lower R,hence power of X is greater than power of Y, hence X is brighter .

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, and the modified set up can measure up to 0.1 A per division, so we say the latter one is more sensitive as it is able to measure smaller change in the currrent.

Based on individual calculations, the highest effective resistance will only be achieved if the junctions are connected at Q and S.

Solutions: Option B Whatever that goes in has to come out. With this basic concept, you will be able to solve this question easily. Ignoring the unknown branch, Total current going into O = 8A + 6A = 14A Total current going out of O = 12A + 4A = 16A Hence in order to be equal, 2A must be flowing in direction PO. Hence answer is B.

The concepts needed to solve such questions Length increases, resistance increases and vice versa. Finding resistors in parallel and in series.