1991 - WAEC Physics Past Questions and Answers - page 3
21
Two forces, whose resultant is 100N are perpendicular to each other. If one of them makes an angle of 60o with the resultant, calculate the magnitude. (Sin 60o = 0.8660, Cos 60o = 0.500)
A
200.0N
B
173.2N
C
115.5N
D
86.6N
22
The graph above shows the expansion of water as the temperature increases from 0oC. Which of the following deductions from the graph are true? i. Water has its maximum density at Q. ii. The volume of water is greater at 0oC than at 4oC. iii. The volume of water decreases uniformly when cooled from 100oC. iv. When water solidifies, its volume increases
A
i and ii only
B
i and iii only
C
ii and iii only
D
i, ii and iii only
correct option: e
Users' Answers & Comments23
Two mirrors are inclined as shown in the diagram. A ray of light RO strikes the arrangement at O and emerges along PO. The emergent ray has been deviated through
A
240o
B
180o
C
120o
D
60o
correct option: b
Users' Answers & Comments24
In the arrangement illustrated above, Y and B are yellow and blue transparent light filters respectively through the filters is
A
blue
B
red
C
yellow
D
green
correct option: e
Users' Answers & Comments25
A ray of light is incident at an angle of 30o on a glass prism of refractive index 1.5. Calculate the angle through which the ray is minimally deviated in the prism. (The medium surrounding the prism is air)
A
10.5o
B
19.5o
C
21.1o
D
38.9o
correct option: a
n = \(\frac{sin i}{sin r}\)
sin r = \(\frac{30^o}{n}\)
sin r = \(\frac{0.5}{1.5}\)
sin r = 0.3333
r = 19.5o; Deviation 30 - 19.5 = 10.5o
Users' Answers & Commentssin r = \(\frac{30^o}{n}\)
sin r = \(\frac{0.5}{1.5}\)
sin r = 0.3333
r = 19.5o; Deviation 30 - 19.5 = 10.5o
26
Calculate the refractive index of the material of the glass block shown in the diagram if YZ = 4cm
A
0.40
B
0.60
C
1.50
D
1.67
correct option: d
n = \(\frac{\text{real depth}}{\text {apparent depth}}\)
\(\frac{10}{10^{-4}}\) = 1.6
Users' Answers & Comments\(\frac{10}{10^{-4}}\) = 1.6
27
An image which can be formed on a screen is said to be
A
virtual
B
blurred
C
inverted
D
erect
correct option: e
Users' Answers & Comments28
Which of the following are true of plane-polarised right? i. Plane polarisation of light is the formation of hydrogen bubbles on the particle of light. ii. Plane components. iii. A plane polarised light vibrates in one plane. iv. Polarisation of light is characteristic of transverse vibration
A
i and ii only
B
i and iv only
C
ii and iii only
D
i and ii only
correct option: d
Users' Answers & Comments29
At which of the following distances from the lens should a slide be placed on a slide projector if f is the focal length of the projector length?
A
less than f
B
greater than f but less than 3f
C
equal to f
D
equal to 2f
correct option: c
Users' Answers & Comments30
what part of the camera corresponds to the iris of the eye?
A
shutter
B
film
C
lens
D
diaphram
correct option: d
Users' Answers & Comments