Waec 1997 Physics Past Questions And Answers
The half-life of a radioactive material is 6hrs. What quantity of 1kg of the material would decay in 24 hours?
- A. 15/16kg
- B. 1/2kg
- C. 1/4kg
- D. 1/16kg
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. Wind speed effects on the speed of sound in air
The odor of a leaking gas is perceived at a distance from the source. This is made possible by the process of
- A. Sublimation
- B. Diffusion
- C. Osmosis
- D. Evaporation
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°
An object falls freely from a height of 25m onto the roof a building 5m high. Calculate the velocity with which the object strikes the roof (g=10\(ms^{-2}\)
- A. 17.3\(ms^{-2}\)
- B. 20\(ms^{-2}\)
- C. 24.5\(ms^{-2}\)
- D. 125\(ms^{-2}\)
Lenz’s law of electromagnetic induction is essentially a statement of the
- A. Inverse square law of gravitation
- B. Inverse square law of magnetism
- C. Inverse square law of electrostatics
- D. Law of conservation of energy
(a) Explain the term resonance and give two examples
(b)(i) Describe, with the aid of a labelled diagram, an experiment to show how the frequency of the note emitted by a vibrating string depends on the length of the string.
(ii) State two precautions necessary to obtain an accurate result.
(c) A sonometer wire is plucked and it vibrates emitting a fundamental note. State the effect on the frequency of the note if the
(i) tension in the wire were made nine times as large with no change in the length of the wire;
(ii) length of the wire were doubled with no change in the tension.
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The current in the primary coil of a transformer is 2.5A. If the coil has 50 turns and the secondary 250 turns, calculate the current in the secondary coil. Neglect energy losses in the transformer
- A. 0.2A
- B. 0.5A
- C. 2.5A
- D. 5A
Which of the following statements about kinetic theory of matter is not correct?
- A. The molecules of matter are always in motion
- B. When a body is heated the average kinetic energy of its molecules decreases
- C. Molecules of a liquid move more freely than those of a solid
- D. Matter is made up of very tiny particles called molecules
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, II and III