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- 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 think of using P = IV. But when using P = IV, it cannot relate to resistance R of the resistors directly. Hence it will be more appropriate for us to P = I^2R or P = V^2/R. For resistors in series , the current is the same. Hence it will be more direct to compare P and R using P = I^2R , where P is directly proportional to R . For resistors in parallel , the p.d. is the same. Hence it will be more direct to compare P and R using P = V^2/R , where P is inversely proportional to R .
- 2013PPP1Q30 – Direction of the electric field around a negative charge
Ans: Option A View the video tutorial for the explanation:
- Understanding cathode-ray oscilloscope CRO
Refer to the notes below together with the video to learn more about the CRO Videos
- Interpreting distance-time graph and speed-time graph
Think of gradient as the steepness of a slope as you climb to the right (as time increases). 1) If it is getting steeper > increasing gradient 2) If it is getting less steep > decrease gradient 3) If it is flat > no/zero gradient For distance-time graph , gradient represents the speed . For speed-time graph , gradient represents the acceleration .
- Scalar and Vector Quantities
Scalar quantity is a quantity with magnitude but no direction. Vector quantity is a quantity with both magnitude and direction .
- Graphs of Transverse Wave
Transverse waves are waves in which travel perpendicular to the direction of vibration of particles.
- Bowling ball and feather in a vacuum room – which drops faster?
In a vacuum room, where is no air resistance, the bowling ball will have the same acceleration as the feather, which is 10 m/s2 on earth. Hence both will have the same speed at any time and reach the floor at the same time. In vacuum, the speed-time graph for both objects will be the same, i.e. straight line, start from origin and with a constant gradient (constant acceleration) of 10 ms-2 due to free-fall acceleration due to gravity.
- Common SI prefixes
Physical Quantity is a quantity that can be measured and it consists of a numerical magnitude (size) and a unit . (e.g. 5m where 5 is the numerical magnitude and m is the unit) 1) The seven base quantities and their SI units Out of the seven, for O level Physics, you are required to learn the first 5 (length, mass, time, current and temperature) . 2) Some common derived quantities and units You can think of base quantities as the smallest building blocks (like Lego bricks). When you combined any base quantities to ‘build’ into something else, they becomes a derived quantity.The derived quantity is ‘derived’ or ‘gotten from’ when 2 or more quantities are combined together. 3) Prefixes for SI units Prefixes are used to represent very large or small quantities.For example, instead of writing 1000000 m, it will be more convenient to write 1Mm, which means the same thing!
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