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Physic-Pract-Answer


1a)
xi(cm)|yi(cm)|zi(cm)|W1(Nx10^-2)|W2(Nx10^-2)|u=(w1-w2)(Nx10^-2)|v=(w1-w3)(Nx10-2)
=>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 

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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.


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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. 


3aiv)
s/n |1|2|3|4|5|6
R(A)|0.00|1.00|2.00|3.00|4.00|5.00|
I(A)|3.00|1.00|0.60|0.41|.035|0.23|
P|0.50|1.50|2.50|3.66|4.29|6.52|


3vi) s=Y1-Y2/X2-X1 =4-2/3.6-1.5 
=2/2.1
=0.952

3vii) C=0.5ohms

3viii)resistance

3ix)
-I would ensure that the circuit is open after each reading to maintain the E.M.F of the battery
-I would ensure that the Zero Error of the Ammeter is checked and noted