JAMB Physics Past Questions & Answers - Page 252

1,256.

The lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 150Hz?

A.

1

B.

2

C.

3

D.

4

Correct answer is B

The fundamental frequency (Fo) =  40Hz

First overtone f1 = 2 \(\times\) 40 = 80

Second overtone f2 = 3 \(\times\) 40 = 120

Third overtone f3 = 4 \(\times\) 40 = 160.

Hence there are just two overtones between 40Hz and 150Hz

1,257.

Which of the following instruments has a pure tone?

A.

guitar

B.

vibrating strings

C.

tuning fork

D.

siren

Correct answer is C

No explanation has been provided for this answer.

1,258.

A boat at anchor is rocked by waves whose crest are 100m apart and whose velocity is 25ms-1. At what interval does the wave crest reach the boat?

A.

2500.00s

B.

75.00s

C.

4.00s

D.

0.25s

Correct answer is C

Distance between the boat and crest = 100m

time = \(\frac{100}{25}\)

= 4sec

1,259.

A wave has a frequency of 2Hz and a wavelength of 30cm. The velocity of the wave is

A.

60.0ms-1

B.

6.0ms-1

C.

1.5ms-1

D.

0.6ms-1

Correct answer is D

V = F\(\lambda\)

= 2 x 0.3

= 0.6ms-1