100% VERIFIED 2016 WAEC GCE PHYSICS PRACTICAL 3 ANSWER

• Item 1 Physics 3 (Alternative to Practical 9.30am – 12.15pm +++++++++++++++++++++++++++++++

  1a ) xi (cm )| yi (cm )| zi (cm )|W 1(Nx 10^ -2)|W 2 (Nx 10 ^ -2 )|u =(w 1 -w 2)(Nx 10 ^ -2)| v =(w 1 -w 3)(Nx 10 -2) =>1 .80 |1 .50 |1 .70 |3 .6| 3. 00| 3. 40| 0. 60|0. 20 =>3 .80 |3 .00 |3 .00 |7 .6| 6. 00| 6. 00| 1. 60|1. 60 =>5 .50 |4 .40 |5 .00 |11 .10 | 8.00 | 10. 00 |2. 20 |1. 00 =>7 .30 |5 .90 |6 .60 |14 .60 | 11. 80 |13 .00 |2. 80 |1. 40 =>9 .20 |7 .30 |8 .30 |18 .40 | 14. 60 |16 .60 |3. 80 |1. 80 =>11 .10 | 8.30 | 10. 00 |22 .20 |16 . 60| 20 .00 |5. 60 |2. 20

  1b)Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity usually means relative density with respect to water.

  1bii) given volume of solid immersed Vsi =1/2*30cm³ =15cm³ Density of liquid (water)ew= 1g/cm³ Acceleration due to gravity, g = 10m/s² Upthrust, U= eVsi g U= 1000*(15*10^-6)*10 U=15*10-² U=0.15N

  Weight of solid =mg =EsVs g given: Es=2.4g/cm³ (2400kg/m³) Vs=30cm (30*10^-6 m³) g=10m/s²

  Weight, w=30*10^-6*2400*10 =72*10-² =0.72N Reading on spring balance =W-U =0.72-0.15 =0.57N ======================

  2ix)I ensured that my lens reading were allinged to avoid parallax errors

  -I ensured that my lens were kept constant all through the reading

  2bi)-It is used for Magnifying glass: For a magnifying glass to work, the object is placed at the focal point such that the image produced is magnified, upright and virtual.

  - It is used in aSlide projector: a projector essentially uses a convex lens to form on a screen a real, magnified and inverted image of the slide or film. The slide, being the object, is positioned between the j and 2f from the lens. =====================

  3) | R/n | I(A) |P=E/I V n^-1 1. |0.00| 3.00 |0.500 2. |1.00| 1.00.|1.500 3. |2.00| 0.60 |2.500 4. |3.00|0.45. |3.333 5. |4.00|0.35. |4.286 6. 5.00 |0.25. |6.000

  

  3vi) S=y2-y1/x2-x1 =4-2/3.6-1.5 =2/2.1 =0.952

  3vii) C=0.5ohms

  3Viii)Resitance

  3ix)-I ensured that the circuit is open after each reading to maintain the E.M.F of the battery

  -I ensured that the Zero Error of the Ammeter is checked and noted

  3b)Internal resistance of a cell is the resistance within a battery, or other voltage source, that causes a drop in the source voltage when there is a current. There is, therefore, actual reduction in the electromotive force of the cell , as well as an increase in internal resistance. ======================

• Item 2