WAEC Past Questions and Answers - Page 3096

15,476.

Economic problem arise in all society because?

A.

Resources are mismanaged by leaders

B.

There is no proper planning

C.

Resources are not in adequate supply

D.

The services of economist are not employed

Correct answer is C

Goods and services that satisfy human wants are produced with the help of resources such as land, labour, capital and enterprise. These resources are scarce while wants are unlimited. Due to scarcity of these resources, an economy cannot produce all that goods and services as required by its citizens.

15,477.

A bar AB is balanced horizontally on two knife edges as illustrated as in the diagram above. Determine the weight of the bar.

A.

10.0N

B.

20.0N

C.

40.0N

D.

50.0N

Correct answer is C

No explanation has been provided for this answer.

15,478.

A simple barometer is constructed using a liquid \(Q_{1}\) of density 16.2\(g/cm^{3}\). Calculate the least lenth of the tube to be used to measure pressure of 1.5atm.  [Density of mercury = 13.6\(g/cm^{3}\), 1atm = 76.0 cm of Mercury]

A.

1358mm

B.

957mm

C.

760mm

D.

638mm

Correct answer is D

Let \(h_{Q}\) and \(\rho_{Q}\) be the least length and the density of \(Q_{1}\) 

while \(h\) and \(\rho\) are the length and density of mercury respectively.

\(h\times \rho \times g = h_{Q} \times \rho_{Q} \times g\)

\(76cm \times 13.6 \times 10 = h_{Q} \times 16.2 \times 10\)

\(h_{Q} = \frac{76\times13.6\times10}{16.2\times10}\)

\(h_{Q} = \frac{10336}{162}\)

\(h_{Q} \approxeq 63.8cm = 638mm\)

15,479.

Which electrical device is illustrated above?

A.

a.c. generator

B.

a.c. motor

C.

d.c. generator

D.

d.c. motor

Correct answer is C

No explanation has been provided for this answer.

15,480.

When two flat plate conductors are arranged in such a way that they possess equal and opposite charges seperated by a dielectric, they form a/an

A.

electroscope

B.

electrophorus

C.

capacitor

D.

cell

Correct answer is C

Most capacitors contain at least two electrical conductors often in the form of metallic plates or surfaces separated by a dielectric medium.