WAEC 2018/2019 physics Practical Obj and Theory/Essay

Physics practical waec 2018 answers
 cares
2ai)
fo=15cm
2av)
a=60.00cm
b=20.00cm
Hence L=a/b=60.00/20.00
L=3
2avi)
TABULATE
S/N:1,2,3,4,5
b(cm):20.00,25.00,35.00,40.00
a(cm):60.00,37.50,30.00,26.25,24.00
L=a/b:3.00,1.50,1.00,0.75,0.60
2avii)
Slope=Change in L/Change in a
=(3-0.25)/(60-18.6)
=2.75/41.4
=0.006642
2aviii)
S^-1=1/S
=(1/0.0066425cm)
S=15.05
S=15cm
2aix)
PRECAUTIONS
-I ensured that all apparatus are in straight line
-I avoided error due to parallax when reading the metre rule
-I avoided zero error on the metre rule
2bi)
u=10cm
f=15cm
Using 1/v+1/u=1/f
1/f-1/u=1/v
1/v=1/15-1/10
1/v=(2-3)/30
1/v=-1/30
v=-30cm
The characteristics of image formed are:
-It is virtual
-It is enlarged and magnified ie twice or two times as big as the object m=2

2bii)
The concave mirror mounted in its holder is moved to and fro in front of the screen until a sharp image of the cross wire of the ray box is formed on the screen adjacent of the object.The distance between the mirror and the screen was measured as 30cm since the radius of curvature r=2fo then half is distance
2bi)
he characteristics of imaged formed are :
i)It is virtual
ii) It is enlarged or magnified i.e. twice or two times bigger as the object(m=2)
[4/4, 09:23] Mic Pedro: 3bii) a) length - longer wires have greater resistance.
     b) thickness - smaller diameter wires have greater resistance.
: Phy - Pract - Answers


1axi)
- *Precautions* -
Take Any Two

i ) I avoided conical oscillation
ii) I avoided drought
iii ) I avoided parallax error in taking reading from the metre rule
iv ) I avoided zero error in taking reading from the stop watch
1b i.
focal length of an object is 20means that the distancebetween the optical centre  or middle of the lens and its principal  focus is 20cm


1bii.
given that u=x   f=20   v=5

using the mirror formula
 1/u   +  1/v  = 1/F

1/x + 1/5 = 1/20

multiply through by the LCM
1/x *5  + 1/5 * 5 = 1/20 * 5

5/x =5/20
5/x =1/4
taking the reciprocal
x/5 =4/1

cross multiply
x * 1 = 5 * 4
x =20
[4/4,
3aix)
- *precautions*-
take any two
i ) I removed key when reading is not taking
ii) I ensured tight connections at the terminals
iii ) I avoided parallax error when taking reading from the ammeter .