2009 - JAMB Physics Past Questions and Answers - page 1
1
The ability of the human eye to focus object on the retina is referred to as the power of
A
interference
B
diffraction
C
accomodation
D
superposition
correct option: c
The leaves collapse as the position charges on the rod neutralize the negative charges on the electroscope
Users' Answers & Comments2
Which of the following is a secondary colour
A
blue
B
orange
C
red
D
green
correct option: b
Primary colours are red, blue and green
∴ orange is a secondary colour
Users' Answers & Comments∴ orange is a secondary colour
3
If negative charges are induced on an electroscope and a positively charged rod is brought near the cap of the electroscope, the leaves will
A
close up
B
become positively charged
C
become negatively charged
D
open further
correct option: a
The leaves collapse as the positive charges on the rod neutralize the negative charges on the electroscope.
Users' Answers & Comments4
An electric lamp marked 240v, 60 W is left to operate for an hour. How much energy is generated by the filament?
A
3.86 x 105J
B
3.56 x 105J
C
1.80 x 104J
D
2.16 x 105J
correct option: d
Energy generated = power X time = 60w x 1h = 60 x 60 x 60 ws = 216000j = 2.16 x 105J
Users' Answers & Comments5
A band of 500 rectangular loops of wire of area 20 cm by 20 cm, encloses a region of magnetic field which charges from 1.0T to 0.4T within 5 seconds, calculate the induced e.m.f.
A
5.60 v
B
24.00 v
C
0.24 v
D
2.40 v
correct option: d
Number of tunes, n = 500
Area, A = 0.2m + 0.2m = 0.4m2
change of flux density A B
= 1.0 - 0.4 = 0.6T
Tune, t = 5 su
Induced emf, ξ = (AB AN)/AT
(0.6 x 0. 04 x 500)/5
= 2.4v
Users' Answers & CommentsArea, A = 0.2m + 0.2m = 0.4m2
change of flux density A B
= 1.0 - 0.4 = 0.6T
Tune, t = 5 su
Induced emf, ξ = (AB AN)/AT
(0.6 x 0. 04 x 500)/5
= 2.4v
6
Cancerous cells can be destroyed by
A
ultraviolet rays
B
alpha particules
C
x - rays
D
infrared rays
correct option: c
Canorous cells can be destroyed with a high penetrating radiation which is x - rays
Users' Answers & Comments7
If the decay constant of a radioactive substance is 0.231s1, the half-life is?
A
3.00 s
B
0.12 s
C
0.33 s
D
1.50 s
8
A piece of radioactive material contains 1020 atoms.
If the half life of the material is 20 seconds, the number of disintegration in the first second is
If the half life of the material is 20 seconds, the number of disintegration in the first second is
A
3.47 x 1018
B
6.93 x 10 20
C
3.47 x 1020
D
6.93 x 1018
correct option: a
The number of disintegration,∆N in time interval At, is given by
- ∆N = N∆t
Where N is the number of atoms present at the time t
But ^ = (0.693)/T
∴ ∆N = (0.693)/1(1)/2 N∆t = (0.693 x 10)20 x 10/20 = 3.47 x 1018
Users' Answers & Comments- ∆N = N∆t
Where N is the number of atoms present at the time t
But ^ = (0.693)/T
∴ ∆N = (0.693)/1(1)/2 N∆t = (0.693 x 10)20 x 10/20 = 3.47 x 1018
9
Thermionic emission is the process whereby
A
β - rays are produced
B
holes are produced
C
x - rays are produced
D
electrons leave a hot element
correct option: d
Thermionic emission is ejection of electron from a metal surface as a result of heating.
Users' Answers & Comments10
Which of the following can conduct electricity owing to the presence of free mobile electrons?
A
germanium
B
silicon
C
grapefruit
D
copper
correct option: d
Metals are good conductors due to the presence of free electrons
Users' Answers & Comments