Physics Past Questions and Answers

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 17:

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 18:

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 19:

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 20:

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