# NECO 2020 PHYSICS PRACTICAL ANSWERS – EXPO RUNS

Paper I: Practical – Physics

# KINDLY CHECK BACK, BEFORE 8AM

(1)
Tabulate.
S/N: 1|2|3|4|5|
M|g: 40.0|35.00|30.00|25.00|20.00|
θ°: 41.80|35.70|30.00|24.60|19.47|
ϕ=(90-θ°): 48.20|54.30|60.00|65.40|70.53|
Cosϕ: 0.6665|0.5835|0.5000|0.4163|0.3333|

(1xi)
Slope , S=Δm|g/ΔCosϕ
=(40-20)g/0.6665-0.3333
S= 20g/0.3332
=60.024g

(1xii)
K=s/2 = 60.024g/g
=30.012g

(1xiii)
-Precautions-
(i) I avoided error due to parallax when reading from the protractor.
(ii) I ensured that the force board is firmly and correctly clamped to the retort stand

(1x)
GRAPH:

(1bi)
They have the same magnitude/size
They can be obtained/calculated by the same means

(1bii)
T² = 9²+12²
T = √81+144
T = √225
T = 15N
=============================================

(3)
Tabulate
S/N: 1|2|3|4|5|
R/Ω: 2.00|4.00|6.00|8.00|10.00|
L/cm: 50.00|66.70|75.00|80.00|83.30|
B/Ω^-¹: 0.500|0.250|0.167|0.125|0.100|
Δ/cm: 1.000|0.499|0.333|0.250|0.200|

(3xiii)
Slope, S=ΔB/Ω^-¹/ΔD/cm = 0.5-0.1/1.0-0.2 = 0.4/0.8=0.5
Slope = 0.5Ω^-¹/cm

(3xiv)
K=S^-¹ = 1/5 = 1/0.5Ω^-¹/cm
=2Ωcm

(3xv)
-PRECAUTIONS-
(i) I avoided error due to parallax when reading from the potentiometer
(ii) I ensured that the wires are tightly connected.

(3)
GRAPH:

(3bi)
(i) Potentiometer give exact value of potential difference while voltmeter draws apart of the current
(ii) Potentiometer can be used for measuring the internal resistance of a cell which cannot be done with a voltmeter.

(3bii)
x/R = c/100 0 – c
x/R = 20-0/100 – 20
x/20 = 20/80
x = 20*20/80
x = 400/80
x= 5Ω 