Nabteb 2017 Physics Practical Answers – May/June Expo

1a)
No of oscillations = 20
Height (h)= 1.0m

Table of observation
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

1aiv)
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

1av) 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

1bi)
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

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

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

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3a)
Standard resistor=1.0~(ohm)
Table of observation
S/N| I(A)| V(v)| I^-1(A^-1)| V^-1(v^-1)

1| 0.4| 0.40| 2.50| 2.50
2| 0.6| 0.60| 1.67| 1.67
3| 0.8| 0.80| 1.25| 1.25
4| 1.0| 1.00| 1.00| 1.00
5| 1.20| 1.20| 0.83| 0.83

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

3avi)
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 opened,to avoid the running down of the battery.

(3bi)
Internal resistance (r): This is the opposition of the current flow through the electrolytic cells.

(3bii)
-Heating effect
-Chemical effect
Heating 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/6 + 1
Cross multiply
6E=9x7
6E=63
Making E subject of formula
E=63/6
=10.5v
So therefore,E.M.F of the cell=10.5v
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