Physics 1994 Waec Past Questions and Answers

Question 46 :

• WAEC 1994

(a) Describe an experiment to show how the frequency of the note emitted by a vibrating string depends on the tension in the string
(b) Draw diagrams showing a vibrating string fixed at both ends emitting (i) fundamental frequency (ii) second overtone indicate the nodes and antinodes on the diagrams
(c) With the aid of a ray diagram show how a virtual image of an object is formed by a (i) concave mirror (ii) converging lens

Question 47 :

• WAEC 1994

(a) Explain what is meant by a magnetic field
(b)(i) Describe an experiment to show that a magnetic field exists around a straight wire carrying current
(ii) Draw a labelled diagram showing the pattern and direction of the magnetic field rroduced around the wire. (Neglect the earth's magnetic field).
(c) Sketch the magnetic field due to two straight parallel wires carrying current in the same direction. Indicate the neutral point in the field
(d) Explain, with the aid of a labelled diagram, how a delicate magnetic material could be protected from the earth's magnetic field.