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Wednesday, 20 May 2026
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Physics Past Questions and Answers

Jamb 1989 Physics Questions

Question 16:
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
View Answer & Explanation
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<sup style='font-size: smaller;'>-8</sup>cm
  • B 5000 x 10<sup style='font-size: smaller;'>-8</sup>cm
  • C 6666 x10<sup style='font-size: smaller;'>-8</sup>cm
  • D 750010<sup style='font-size: smaller;'>-8</sup>cm
View Answer & Explanation
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
View Answer & Explanation
Question 19:
The plane mirrors in a kaleidoscope are usually placed
  • A At an angle of 60<sup style='font-size: smaller;'>o</sup>
  • B Parallel to one another
  • C Perpendicular to one another
  • D At an angle of 45<sup style='font-size: smaller;'>o</sup>
View Answer & Explanation
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
View Answer & Explanation