Which of the following statements about the electromagnetic waves is correct?
radio waves have longer frequencies than x-rays
x-rays have the longest wavelength
some of the waves travel at 3.0 x 108ms-1
white light occupies a region beyond ultraviolet rays
Correct answer is D
All electromagnetic waves: are transverse waves; can travel through a vacuum ; travel at exactly the same speed in a vacuum, the speed of light, 300,000,000 m/s.
The common designations are radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV) light, X-rays and gamma-rays.
ultraviolet rays lie beside violet of visible light and has a lesser frequency than visible light.
The main difference between echo and reverberation is that
reverberation is reflected sound while echo is refracted sound
the time interval between incident sound and reflecte sound is shorter for reverbration
the amplitude of an echo is greater
reverberation is from acoustic speakers while echo comes from cliffs
Correct answer is B
No explanation has been provided for this answer.
Two sound waves have frequencies of 12Hz and 10Hz. Calculate their beats period
0.5s
1.0s
1.2s
2.0s
Correct answer is A
\(f_1 - f_2 = \frac{1}{T}\)
12 - 10 = \(\frac{1}{2}\)
= 0.5
\(\frac{f_2}{f_1}\)
1 - \(\frac{f_2}{f_1}\)
\(\frac{f_2}{f_1}\) - 1
\(\frac{f_1}{f_2}\)
Correct answer is A
No explanation has been provided for this answer.
Presbyopia is a defect of the eye resulting from
weak ciliary muscles
short eyeball
loss of sphericity of the lens
long eyeball
Correct answer is A
No explanation has been provided for this answer.