# 2017 - JAMB Physics Past Questions & Answers - page 1

1
Which is the incorrect formula for a body accelerating uniformly?
A
a = v2 − u$$\frac{2}{2}$$
B
v2 = u2 + 2as
C
s = $$\frac{1}{2}$$ut + at2
D
v2 − u2= 2as
CORRECT OPTION: c
s = $$\frac{1}{2}$$ut + at2 is a wrong equation, it should be s = $$\frac{1}{2}$$ut + at2
2
Which of the following is not an electromagnetic radiation?
A
x - ray
B
C
sunlight
D
sound waves
CORRECT OPTION: d
Electromagnetic waves do not require any material medium, but sound waves is a mechanical wave that require a material medium
3
Calculate the electric field intensity between two plates of potential difference 6.5V when separated by a distance of 35cm.
A
18.57NC$$^{-1}$$
B
53.06N C$$^{-1}$$
C
2.28NC$$^{-1}$$
D
0.80NC$$^{-1}$$
CORRECT OPTION: a
Electric Field Intensity (E) = $$\frac{v}{d}$$

= $$\frac{\text{potential difference}}{\text{distance}}$$

= $$\frac{6.5v}{35cm}$$

= $$\frac{6.5}{35 \times 10^{- 2}}$$

= 18.57NC$$^{-1}$$
4
Why do soldiers march disorderly while crossing a bridge?
A
To prevent resonance on the bridge
B
To set the bridge into resonance
C
To make the b ridge collapse
D
To spread their weight evenly on the bridge
CORRECT OPTION: a
Soldiers march disorderly while crossing a bridge to prevent resonance because when soldiers march in orderly manner across a bridge, they generate a rhythmic oscillation of wave out. The bridge and at a certain point, would start oscillation to the same rhym as that of the marching steps. This oscillation would reach a maximum peak when the bridge can no longer sustain its own strength and hence collapses. So for this reasons, soldier are ordered to march disorderly while crossing a bridge
5
Calculate the upthrust on an object of volume 50cm3 which is immersed in liquid of density 103kgm-3 [g = 10ms-2]
A
0.8N
B
2.5N
C
0.5N
D
1.0N
CORRECT OPTION: c
Upthrust = change in weight

density = $$\frac{\text{mass}}{\text{volume}}$$

Mass of liquid displaced = Density of Liquid × Volume;

= 103 × 50 × 10− 6m3

= 0.05kg

(Note that the volume of 50cm3 was converted to m3 by multiplying by 106) i.e 50cm3 = 50 × 10−6m3)

Since mass displaced = 0.05kg

Upthrust = mg = 0.05 × 10

= 0.5N
6
Under what conditions are cathode rays produced in a discharge tube?
A
High pressure and low voltage
B
High pressure and high voltage
C
Low pressure and low voltage
D
Low pressure and high volatge
CORRECT OPTION: d
Cathode rays are produced in a discharge tube under Low pressure and high voltage
7
Under which of the following conditions is workdone
A
A man supports a heavy food above his head with his hands
B
A boy climbs onto a table
C
A man pushes unto a table
D
A woman holds a pot of water
CORRECT OPTION: b
For work to be done, distance must be involved because
workdone = force × distance
8
Calculate the specific latent heat of vaporization of steam of 1.13 x 106J pf heat energy is required to convert 15kg of it to water.
A
7.53 x 105 Jkg$$^{-1}$$
B
7.53 x 10-2Jkg$$^{-1}$$
C
7.53 x 104Jkg$$^{-1}$$
D
7.53 x 10-3Jkg$$^{-1}$$
CORRECT OPTION: c
Latent Energy = mass(m) × specific latent heat (L)
ε = mL

L = ε/m$$\frac{E}{m}$$

= $$\frac{1.13 \times 106}{15}$$

= 7.53 × 104Jkg$$^{-1}$$
9
A cell of internal resistance 2 π supplies current to a 6 π resistor. The efficiency of the cell is
A
12.0%
B
25.0%
C
33.3%
D
75.0%
CORRECT OPTION: c
Internal resistance determine the maximum current that can be supplied

Efficiency = $$\frac{r}{R}$$ × 100

= $$\frca{2}{6}$$ × 100

= 33.3%
10
Which of the following statements is NOT correct?
A
Molecules of a liquid are stationary
B
Brownian motion is an evidence of particle nature of matter
C
Matter is made up of molecules
D
The molecules of matter are in constant motion
CORRECT OPTION: a
Molecules of liquid are not stationary
Brownian motion is an evidence of particle nature of matter
matter is made up of molecules
The molecules of matter are in constant motion
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