WAEC Past Questions and Answers - Page 2951

14,751.

Which property of a wave remains constant when the wave travels from one medium into another?
 

A.

Amplitude

B.

Wavelength

C.

Velocity

D.

Frequency

Correct answer is D

Frequency remains unchanged as waves travel from one medium to another because it is characterized by the source of the wave.

14,752.

An election held to fill a vacant post in the legislature due to the death or resignation of a member is called

A.

run - off election

B.

electoral college

C.

bye - election

D.

primary elections

Correct answer is C

Bye- election;  is an election used to fill an office that has become vacant between general elections

14,753.

A device consumes 100 W of power when connected to a 120 V source. Calculate its resistance

A.

1.2\(\Omega\)

B.

12,000 \(\Omega\)

C.

20.0\(\Omega\)

D.

144\(\Omega\)

Correct answer is D

P = \(\frac{V^2}{R}\) 

R = \(\frac{120^2}{100}\)

= 144.0\(\Omega\) 

14,754.

Politics is practically demonstrated during

A.

electioneering campaigns

B.

parliamentary debates

C.

formation of political parties

D.

inter-party consultative meetings

Correct answer is A

Electioneering campaign;  refers to the act of campaigning to influence the result of an election in favor of a particular candidate or party.

14,755.

An electron of mass 9.1 x 10\(^{-31}\) kg moves with a speed of 2.0 x 10\(^6\) ms\(^{-1}\) round the nucleus of an atom in a Circular path of radius

6.1 x 10\(^{11}\) m. Calculate the centripetal force acting on the electron.
 

A.

7.7 x 10\(^{47}\) N

B.

6.0 x 10\(^{-8}\)N

C.

3.0 x 10\(^{-14}\)N

D.

1.3 x 10\(^{-26}\)N

Correct answer is B

Centripetal force (Fr) = \(\frac{MV^2}{r}\) 

i.e. Fr = \(\frac{Mv^2}{r}\) 

= \(\frac{9.1 \times 10^{-31} \times 2.0 \times 10^6 \times 2.0 \times 10^6}{6.1 \times 10^{-11}}\) N 

= (\(\frac{36.4 \times 10^{-19}}{6.1 \times 10^{-11}}\)) N

= 5.967 x 10\(^{-8}\) N 

~ 6.0 x 10\(^{-8}\) N