1997 - WAEC Physics Past Questions and Answers - page 4
31
Two identical waves traveling in the same direction are superimposed. What should be the phase difference between the waves for maximum destructive interference to occur?
A
20°
B
45°
C
180°
D
225°
correct option: c
Users' Answers & Comments32
When a resistor of resistance R is connected across a cell, the terminal p.d of the cell is reduced to three quarters of its e.m.f. The internal resistance of the cell is expressed as
A
R/4
B
R/3
C
R/2
D
3R/4
correct option: b
Users' Answers & Comments33
A pipe open at both ends, produces a fundamental note. If the velocity of sound in air is V and L the length of the pipe, which of the following expresses the frequency of the note? Neglect end correction
A
2V/L
B
V/2L
C
V/3L
D
V/4L
correct option: b
Users' Answers & Comments34
Which of the following statements is not correct?
A
The pitch of a note depends on the frequency of the vibrating source
B
The loudness of a note depends on its intensity
C
The velocity of sound in air does not depend on the intensity of the note producing it
D
The overtones present in a note determine its quality
correct option: e
Users' Answers & Comments35
A progressive wave has a wavelength of 50cm. calculate the phase difference between two points at a distance of 20cm apart.
A
10/3π
B
5/2 π
C
4/5 π
D
2/3 π
correct option: c
Phase difference = \(\frac{2\pi x}{\lambda}\)
= \(\frac{2\pi \times 20}{50}\)
= \(\frac{4}{5} \pi\)
36
An alternating current with a peak value of 5A passes through a resistor of resistance 10Ω. Calculate the rate at which energy is dissipated in the resistor
A
250W
B
125W
C
50W
D
35.4W
37
The invisible part of the spectrum of a white light consists of the following colors
A
Red, orange and yellow only
B
Infra-red, ultraviolet and blue only
C
Indigo and green only
D
Violet and red only
correct option: e
Users' Answers & Comments38
Which of the following is not true of the similarities between a camera and the human eye?
A
Both the camera and the human eye have light proof interiors
B
Both the camera and the human eye have light sensitive screens
C
Inverted images are formed on the screen in both
D
The distance between the lens and the screen is fixed in both
correct option: d
Users' Answers & Comments39
The magnification produced with a converging lens is 5. If the object is a square wire gauze of side 2cm, calculate the area of the image
A
100\(cm^3\)
B
40\(cm^3\)
C
20\(cm^3\)
D
10\(cm^3\)
correct option: c
Users' Answers & Comments40
A magnet is being inserted into a coil of wire. On which of the following factors does the induced e.m.f in the coil depend? I. Number of turns in the coil II. Strength of the coil III. Speed with which magnet is inserted into the coil.
A
I only
B
II only
C
III only
D
I and II only
correct option: e
Users' Answers & Comments