Question 541:

• JAMB 1989

In a sound wave in air, the adjacent rarefactions and compressions are separated by a distance of 17cm. If the velocity of the sound wave is 340ms^-1. Determine the frequency

A. 10Hz
B. 20Hz
C. 1000Hz
D. 5780Hz

Question 542:

• JAMB 1989

Light of wavelength 5000 x 10^-8cm travels in free space with a velocity of 3 x 10⁸ms^-1. What is its wavelength in glass of refractive index 1.5?

A. 3333 x 10^-8cm
B. 5000 x 10^-8cm
C. 6666 x10^-8cm
D. 750010^-8cm

Question 543:

• JAMB 1989

The magnification of the image of an object placed in front of a convex mirror is \(\frac{1}{3}\). If the radius of curvature of the mirror is 24cm, what is the distance between its object and its image?

A. 8cm
B. 16cm
C. 24cm
D. 32cm

Question 544:

• JAMB 1989

The plane mirrors in a kaleidoscope are usually placed

A. At an angle of 60^o
B. Parallel to one another
C. Perpendicular to one another
D. At an angle of 45^o

Question 545:

• JAMB 1989

A far sighted person cannot see objects that are less than 100cm away. If this person wants to read a book at 25cm, what type and focal length of lens does he need?

A. Convex, 20cm
B. Concave, 20cm
C. Convex, 33cm
D. Concave, 33cm