NABTEB Physics Practical Expo Answer – May/June 2017

1)a)
No of oscillation = 20
Height h = 1.0m

Table of values
S/N. Y(cm) t(s) T-t/20(s) T^2
1. 10.00. 38.00. 1.90. 3.62
2. 20.00. 35.80. 1.79. 3.22
3. 30.00. 33.60. 1.68. 2.82
4. 40.00. 31.20. 1.56. 2.42
5. 50.00. 28.40. 1.42. 2.01

1)aiv)
Slope = ΔY/ΔT^2
=62-10/1.5-3.6
=52/-2.1
=24.76cm/s^2
Intercept I, on the vertical axis=88cm or 0.88cm

1)avi) precautions
-i avoided error due to parallax when reading the stopwatch and metre rule
-i ensured that the Bob was displaced through the small angle to avoid conical oscillation

1)bi)
Period:is the time taken or required to complete one oscillation or to and fro movement
Frequency:is the number of cycle or oscillation complete in one seconds

1)bii)
-the shape of the earth (spherical)
-Distance of the object from its centre

1)biii)
Diameter d=2.4m radius r=1.2m velocity v=8m/s
V=wr
Making W subject of the formula
W=v/r
=8/1.2
=6.67rads^-1

3a)
Standard resistor=1.0~(ohm)
Table of values
S/N. I(A) V(v) I^-1(A^-1) V^-1(v^-1)
1. 0.4. 0.40. 2.500. 2.500
2. 0.6. 0.60. 1.670. 1.670
3. 0.8. 0.80. 1.250. 1.250
4. 1.0. 1.00. 1.000. 1.000
5. 1.20. 1.20. 0.830. 0.830

3a)v)
Slope, s =ΔI^-1/ΔV^-1
=3.0-0.5/3.0-0.5
=2.5/2.5
=1.0V/A

3a)vi)
From, S=ΔI^-1/ΔV^-1
1.0=V/0.75
V=0.75v

(3avii)
PRECAUTIONS:
-i ensured tight connections of connecting wires.
-I ensured that the key was open,to avoid the running down of the battery.

(3bi)
Internal resistance (r)-this is the opposition of current flow through the electrolytic cells.
(3bi)
-heat effect
-chemical effect
Heat effect is used in electric cooker for cooking.

(3biii) ~ is donated with ohms
r=1~ , R=6~ , V=9v , E=?
I=E/R+r
V/R=E/R+r
9/6=E/R+r
Cross multiply
6E=9×7
6E=63
Making E subject of formula
E=63/3
=10.5v
So therefore,E.M.F of the cell=10.5v
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