2008 - JAMB Physics Past Questions and Answers - page 2
11
When cold water is poured on a can containing hot water, the can collapses because the
A
steam condeses and occupies the partial vacuum in the can
B
external air pressure counter balances the pressure within the can
C
steam expands to occupy the vacuum remaining in the can
D
external pressure becomes greater than the pressure within the can.
correct option: d
Cold water reduces the temperature of the hot water inside the can causing the contraction of the hot water. This reduces the pressure inside the can and the can collapses due to the external greater expression.
Users' Answers & Comments12
An empty density bottle weighs 2 N. if its weighs 5 N when filled with water and 4 N when filled with olive oil, the relative density of olive oil is
A
(1)/3
B
(2)/3
C
(1)/5
D
(2)/5
correct option: b
relative density = (weight of substance )/weight of equal volume of water = (4 - 2)/5 - 2 = (2)/3
Users' Answers & Comments13
The thermometric properties of a thermocouple is the change in?
A
equivalent resistance
B
electromotive force
C
colour
D
pressure
correct option: b
Temperature difference between hot and cold junctions of thermocouple is proportional to the emf. generated
Users' Answers & Comments14
During summer, the balance wheel of a clock expands.what effect does this have on the accuracy of the clock?
A
the clock gians time
B
the accuracy of the clock is not affected
C
the clock losses time
D
the clock stops working
correct option: c
The elastic potential energy of the balance wheel reduces as the wheel expands, therefore the clock will loose time.
Users' Answers & Comments15
A sealed flask contains 600cm3 of air at 27°C and is heated to 35°C at constant pressure. The new volume is?
A
508 cm3
B
516 cm3
C
608 cm3
D
616 cm3
correct option: d
V1 = 600cm3, T1 = 27 = 273 = 300k
T2 = 35 + 273 = 308K, V2 = ?
(V)1/T1
= (V)2/T2 = V2
= (V)1/T1 x X T2
= (600 X 308)/300 = 616 cm3
Users' Answers & CommentsT2 = 35 + 273 = 308K, V2 = ?
(V)1/T1
= (V)2/T2 = V2
= (V)1/T1 x X T2
= (600 X 308)/300 = 616 cm3
16
A block of aluminum is heated electrically by a 25 W heater. if the temperature rises by 10°C in 5 minutes, the heat capacity of the aluminum is?
A
850 JK-1
B
750 JK-1
C
650 JK-1
D
500 JK-1
correct option: b
Heat supplied = Heat gained
P x t = C ∆ Ø
(25 x 5 x 60)/300 = 750 JK-1
Users' Answers & CommentsP x t = C ∆ Ø
(25 x 5 x 60)/300 = 750 JK-1
17
If the partial pressure of water vapour at 27°C is 18 mm Hg and the saturated vapour pressure of the atmosphere at the same temperature is 24 mm Hg, the relative humidity at this temperature is?
A
25%
B
33%
C
75%
D
82%
correct option: c
Relative
Humidity = (S.V.P. of water at dew point)/S.V.P of water at air temperature =(18)/24 x 100% = 75%
Users' Answers & CommentsHumidity = (S.V.P. of water at dew point)/S.V.P of water at air temperature =(18)/24 x 100% = 75%
18
In a good thermos flask, the main cause of heat loss is?
A
conduction through the cork
B
the plastic base of the thermos flask
C
the silvered walls and shiny metals
D
the outer cover or jacker
correct option: a
Since the cork is in contact with the walls of the flask, little conduction takes place
Users' Answers & Comments19
Given the progressive wave equation y = 5 sin (2000 πt - 0.4x), calculate wave length
A
12.4 m
B
15.7 m
C
17.5 m
D
18.6 m
correct option: b
Comparing y = 5sin (200 πt - 0.4X) with the wave equation y = A sin (wt -KX) K = (2π)/λ = 0.4
∴ λ = (2π)/0.4 = 15.7M
Users' Answers & Comments∴ λ = (2π)/0.4 = 15.7M
20
The fundamental property of a propagating wave which depends only on the source and not the medium of propagation is the?
A
wavelength
B
harmonies
C
frequency
D
velocity
correct option: b
Timber/ quality depends on the overtones or harmonics, and timber is a characteristic property of source of sound.
Users' Answers & Comments