1993 - JAMB Physics Past Questions and Answers - page 2
11
A metal rod 800mm long is heated from 10oC to 95oC. If it expands by 1.36mm, the linear expansivity of the metal is
A
2.0 x 102K-1
B
2.0 x 102K-1
C
5.0 x 10-3K-1
D
2.0 x 10-5K-1
12
When the volume of a given mass of gas is halved and its temperature doubled, the pressure
A
remains constant
B
increases by a factor of 4
C
increases by a factor of 3
D
decreases by a factor of 4
correct option: b
\(\frac{P_1V_1}{T_1}\) = \(\frac{P_2V_2}{T_2}\)
V1 = 2V2 and T2 = 2T1
\(\frac{P_1\times 2V_2}{T_1}\) = \(\frac{P_2\times V_2}{2T_1}\)
P2 = 4P1
Users' Answers & CommentsV1 = 2V2 and T2 = 2T1
\(\frac{P_1\times 2V_2}{T_1}\) = \(\frac{P_2\times V_2}{2T_1}\)
P2 = 4P1
13
200g of water at 90oC is mixed with 100g of water at 30oC. What is the final temperature?
A
50oC
B
60oC
C
70oC
D
80oC
correct option: c
Heat lost = heat gained
200 x c x (90 - \(\theta\))
\(\theta\)= 70oC
Users' Answers & Comments200 x c x (90 - \(\theta\))
\(\theta\)= 70oC
14
The relationship between L and the wavelength I of the stationary wave is
A
2L = \(\lambda\)
B
L = \(\lambda\)
C
L = \(\frac {\lambda}{3}\)
D
4L = 3 \(\lambda\)
15
Determine the distance between the consecutive antinodes XX if the wavelength is 66cm
A
15cm
B
30cm
C
60cm
D
120cm
correct option: b
Distance XX = \(\frac{1}{2}\)\(\lambda\)
= \(\frac{1}{2}\) x \(\frac{60}{1}\)
= 30cm
Users' Answers & Comments= \(\frac{1}{2}\) x \(\frac{60}{1}\)
= 30cm
16
Which of the following waves can propagate through a vacuum?
A
High velocity sound waves
B
Ultrasonic waves
C
Acoustic waves
D
Infra-red waves
correct option: d
Users' Answers & Comments17
Radio waves emitted from an antenna are picked up by a radar after reflection from an aircraft in 4 x 10-3S. How far is the aircraft from the antenna? [c = 3 x 108ms-1 ]
A
6.0 x 102ms-1
B
1.2 x 103km
C
3.0 x 103km
D
6.0 x 10 5km
correct option: d
Time = 1 x 4 x 10-3sec
distance = velocity x time
= 3 x 108 x 4 x 10-3
= 6 x 105m
Users' Answers & Commentsdistance = velocity x time
= 3 x 108 x 4 x 10-3
= 6 x 105m
18
Which of the following expressions gives the linear magnification produced by a concave mirror of radius of curvature r, if U and V are the object and image distances respectively?
A
\(\frac{V}{r}\) - 1
B
\(\frac{2V}{r}\) - 1
C
\(\frac{U}{r}\) - 1
D
\(\frac{2U}{r}\) - 1
correct option: d
F = \(\frac{r}{2}\) and v = mu
F = \(\frac{UV}{U + V}\)
\(\frac{r}{2}\) = \(\frac{U \times mu}{U + mu}\)
\(\frac{r}{2}\) = \(\frac{mu^2}{V(1 + m)}\)
m = \(\frac{2u}{r}\) - 1
Users' Answers & CommentsF = \(\frac{UV}{U + V}\)
\(\frac{r}{2}\) = \(\frac{U \times mu}{U + mu}\)
\(\frac{r}{2}\) = \(\frac{mu^2}{V(1 + m)}\)
m = \(\frac{2u}{r}\) - 1
19
If the focal length of a camera lens is 20cm, the distance from the film at which the lens must be set to produce a sharp image of an object 100cm away is
A
17cm
B
20cm
C
25cm
D
100cm
correct option: c
F = \(\frac{uv}{u + v}\)
20 = \(\frac{100 \times v}{100 + v}\)
v = 25cm
Users' Answers & Comments20 = \(\frac{100 \times v}{100 + v}\)
v = 25cm
20
Which of the following may be used to explain a mirage? i. layers of air near the road surface have varying refractive indices in hot weather. ii. road surfaces sometimes become good reflectors in hot weathers. iii. light from the sky can be reflected upwards after coming close to the road surface.
A
ii only
B
ii and iii only
C
i and iii only
D
i, ii, and iii only
correct option: c
Users' Answers & Comments