2015 - JAMB Physics Past Questions and Answers - page 3
21
Radio waves belong to the class of wave whose velocity is about
A
34m/s
B
3 ×106m/s
C
3 ×108m/s
D
3 × 10-8m/s
correct option: c
A radio waves is an electromagnetic waves which travels with a constant velocity of 3 × 108m/s
Users' Answers & Comments22
At 35°C and 5 atmospheres pressure the density of a gas is 0. 600g per liter. What is the density at 7 atmospheric pressure and 350°C.
A
0.27g / liters
B
0.25g / liters
C
17g / liters
D
0.15g / liters
correct option: c
\( \theta1 = 35°C T1 = 273 + θ = 73 + 35 = 308k P1 = 5 \)atm
d1 = 0.600g/ litre
θ2 = 350°C, T2 = 2 + 3 + θ
= 273 + 350 = 623k, d2 = ?
P2 = 7atm
T a P a 1/d = TPK/d (where k is a constant)
Tp1 ÷ d1 = T1P2 ÷ d2, [(308 × 5) ÷ 0.600]
= (623 × 7) ÷ d2
d2 = (623 × 7 ×0.600) ÷ (308 × 5)
= 2616.6 ÷ 1540
= 1.69g / litresd2 = 1.69g / litres
∴ d2 = 1.70g / litres (Approx.)
Users' Answers & Commentsd1 = 0.600g/ litre
θ2 = 350°C, T2 = 2 + 3 + θ
= 273 + 350 = 623k, d2 = ?
P2 = 7atm
T a P a 1/d = TPK/d (where k is a constant)
Tp1 ÷ d1 = T1P2 ÷ d2, [(308 × 5) ÷ 0.600]
= (623 × 7) ÷ d2
d2 = (623 × 7 ×0.600) ÷ (308 × 5)
= 2616.6 ÷ 1540
= 1.69g / litresd2 = 1.69g / litres
∴ d2 = 1.70g / litres (Approx.)
23
The compressed regions and the space-out regions in longitude wave are refers to as
A
Compression and Rarefaction
B
Comparison and Explosion
C
Reflection only
D
Refraction only
correct option: a
The vibrating particles behave like a spiral spring with a series of compression region and space–out region.
Users' Answers & Comments24
At what respective value of a, b, and c would the unit of work, the joule, be dimensionally similar to Ma Lb Tc?
A
1, – 2, 1
B
1, 2, – 2
C
1, 1, –2
D
2, 2, 1
correct option: b
Work (w) = Force (f) × Distance (d)
Note: f = ma = mass × acceleration
= mass ×acceleration ×distance
= kg ×ms–2 × m
= kg m2 5–2
(Note: the dimension of kg = M, M = L & S = T)
Work = ML2 T–2 = Ma Lb Tc
i.e. Ma Lb Tc = as 1, b = 2, c = –2
The value of a, band c = 1, 2, –2
Users' Answers & CommentsNote: f = ma = mass × acceleration
= mass ×acceleration ×distance
= kg ×ms–2 × m
= kg m2 5–2
(Note: the dimension of kg = M, M = L & S = T)
Work = ML2 T–2 = Ma Lb Tc
i.e. Ma Lb Tc = as 1, b = 2, c = –2
The value of a, band c = 1, 2, –2
25
The device in which one circuit controls another, especially if the current in the second circuit is large or dangerous is known as
A
Electromagnetic devices
B
Magnetic relay device
C
None at all
D
Sextant
correct option: b
Magnetic relay device :is the device that controls a circuit (i.e one circuit )if a current in the second circuit is large or dangerous
Users' Answers & Comments26
Heat losses to the surrounding is possible through the following except
A
Conduction
B
Convection
C
Radiation
D
Expansion
correct option: d
Conduction, conveying of heat or electricity through a material medium is required
Users' Answers & Comments27
Quantities of heat Q can be measured using a container called
A
Thermometer
B
Measuring cylinder
C
Calorimeter
D
Meter rule
correct option: c
Calorimeter is an apparatuses used for measuring the heat (Q) generated or absorbed by change of phase (state) or other physical change
Users' Answers & Comments28
Lodestone is a natural magnet, it points at
A
N – W when suspended freely
B
N–S when suspended freely
C
S – E when suspended freely
D
S–W when suspended freely
correct option: b
Lodestone is a natural magnet it points approximate at N – S when suspended freely
Users' Answers & Comments29
What type of electromagnetic radiation can be used to take photographs in the haze?
A
Radio waves
B
infrared rays
C
Visible light
D
Gamma rays
correct option: b
Infrared rays are easily detected by special photographic films and it can be used for taking picture in haze
Users' Answers & Comments30
If a mango fruit dropped at a height of 50 meters. How long does it reach the ground? (take g = 10m/s2)
A
2 sec
B
3 sec
C
4sec
D
3.2sec
correct option: d
From S = ut + ½gt2
u = 0ms-1
50 = (0 × t) + ½(10)(t2)
50 = 5.0t2
t2 =50/5
t = √10
t = 3.2sec
Users' Answers & Commentsu = 0ms-1
50 = (0 × t) + ½(10)(t2)
50 = 5.0t2
t2 =50/5
t = √10
t = 3.2sec