WAEC Physics 2007 Past Questions

 A particle is projected at an angle of 30° to the horizontal with a speed of 250 ms\(^{-1}\). Calculate the;

(a) total time of flight of the particle;

(b) speed of the particle at its maximum height. [ g = 10 ms\(^{-2}\)]

State;

(a) the difference between plane polarized light and ordinary light;

(b) two uses of polaroids.

Define

(a) electrolysis;

(b) electrolyte;

(c) electrode.

Copper of thickness d is plated on the cathode of a copper voltameter. If the total surface area of the cathode is 60 cm\(^2\) and a steady current of 5.0 A is maintained in the voltameter for 1 hour. calculate the value of d. [density of copper = 8.9 x 10\(^3\)kg m\(^{-3}\) electro chemical equivalent of copper = 3.3 x 10\(^{-7}\) kg C\(^{-1}\)

(a) Explain thermiopic emission

(b) State two applications of electrical conduction through gases.

A wire of length 5.0 m and diameter 2.0 mm extends by 0.25 mm when a force of 50 N was used to stretch it from its end. Calculate the;

(a) stress on the wire;

(b) strain in, the wire. [\(\pi = 3.142\)]

(a) List two factors that can affect the rate of diffusion
(b) State two examples to illustrate the effects of surface tension.

State two effects to show (a) the existence of matter waves;

(b) that radiation behaves like particles.

A stone projected horizontally from the top of a tower with a speed of 4 ms\(^{-1}\) lands on the level ground at a horizontal distance 25 m from the foot of the tower. Calculate the height of the tower. g = 10 ms\(^{-2}\)]

Define (a) tensile Stress; (b) tensile strain; (c) yield point.

(a) State the conditions of equilibrium for a number of coplanar parallel forces.

(b) A metre rule is found to balance horizontally at the 48 cm mark. When a body of mass 60 g is suspended at the 6 cm mark, the balance point is found to be at the 30 cm mark. Calculate the;

(i) mass of the metre rule;

(ii) distance of the balance point from the zero end, if the body were moved to the 13 cm mark.

(c) a man pulls up a box of mass 70 kg using an inclined plane of effective length 5 m unto a platform 2.5 m high at a uniform speed. If the frictional force between the box and the plane is 1000 N;

(i) draw a diagram to illustrate all the forces acting on the box while in motion;

(ii) calculate the I. minimum effort applied in pulling up the box; II. velocity ratio of the plane, if it is inclined at 30° to the horizontal; Ill. force ratio of the plane.

(a) Define the boiling point of a liquid.

(b) With the aid of a sketch diagram, describe an experiment to determine the boiling point of a small quantity of a Iiquid

(c) A piece of copper of mass 300 g at a temperature of 950°C is quickly transferred into a vessel of negligible thermal capacity containing 250 g of water at 25°C. If the final steady temperature of the mixture is 100°C, calculate the mass of water that will boil away. Especific heat capacity of copper = 4.0 x 10\(^2\) J kg\(^{-1}\)K\(^{-1}\)  specific heat capacity of water = 4.2 x 10\(^{3}\) J kg\(^{-1}\)K\(^{-1}\) specific latent heat of vaporization of steam = 2.26 x 10\(^6\)J kg\(^{-1}\)

(a)(i) What is a wave motion?

(ii) State two differences between a radio wave and a sound wave.

(b)(i) Given that you are provided with a tuning fork, a burette and other necessary apparatus, describe with the aid of a diagram, an experiment to determine the frequency of a note emitted by a source of sound. [assume the velocity of sound in air is known]

(ii)State two precautions necessary to obtain accurate result in the experiment described in (b)(i) above

(c) A pipe closed at one end is 100 cm long. If the air in the pipe is set into vibration and a fundamental note is produced, calculate the frequency of the note. [ velocity of sound in air = 340 ms\(^{-1}\)]

(a) With the aid of a simple diagram, explain how a step down transformer works.

(b)(i) State three ways by which energy is lost in a transformer

(ii) Mention how each of the losses in (b)(i) above can be minimized

(c) A 95% efficient transformer is used to operate a lamp rated 60W, 220 V from a 4400 V a.c supply. Calculate the;

(i) ratio of the number of turns in the primary coil to the number of turns in the secondary coil of the transformer

(ii) current taken from the main circuit.

(a)(i) With the aid of a labelled diagram describe the mode of operation of a modern X-ray tube.

(ii)State the energy transformations that take place during the operation of the X-ray tube.

(b) Define, as applied to X-rays, the following terms:

(i) hardness;

(ii) intensity.

(c) State (i) four uses of X-rays;

(ii) one hazard of over-exposure to X-rays in a radiological laboratory.