Light Practice Questions
WAEC (West Africa) · WAEC Physics · 135 free MCQs with instant results and detailed explanations.
135
Total
42
Easy
71
Medium
22
Hard
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Sample Questions from Light
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Q1
Easy
What is the speed of light in a vacuum?
A.
3 x 10^8 m/s
B.
3 x 10^6 m/s
C.
3 x 10^10 m/s
D.
3 x 10^4 m/s
Show Answer & Explanation
Correct Answer: A
The speed of light in a vacuum is approximately 3 x 10^8 meters per second, which is a fundamental constant of nature.
Q2
Easy
What is the speed of light in a vacuum?
A.
3 x 10^8 m/s
B.
1 x 10^6 m/s
C.
5 x 10^7 m/s
D.
2.5 x 10^8 m/s
Show Answer & Explanation
Correct Answer: A
The speed of light in a vacuum is approximately 3 x 10^8 meters per second. This is a fundamental constant of nature and is often denoted by 'c'.
Q3
Easy
When light passes from air into water, what happens to its speed?
A.
It increases
B.
It decreases
C.
It remains constant
D.
It becomes zero
Show Answer & Explanation
Correct Answer: B
When light passes from air (less dense medium) into water (more dense medium), its speed decreases due to the higher optical density of water.
Q4
Medium
What is the phenomenon called when light bends as it passes from one medium to another?
A.
Refraction
B.
Reflection
C.
Dispersion
D.
Diffraction
Show Answer & Explanation
Correct Answer: A
Refraction occurs when light travels from one medium to another, changing speed and direction due to the difference in optical densities.
Q5
Medium
If the angle of incidence is 30° in air, what is the angle of refraction when light enters water (n = 1.33)?
A.
22.5°
B.
30°
C.
23.5°
D.
15°
Show Answer & Explanation
Correct Answer: C
Using Snell's law (n1 * sin(theta1) = n2 * sin(theta2)), we find that sin(theta2) = (1 * sin(30)) / 1.33, leading to theta2 ≈ 23.5°.
Q6
Medium
A prism can disperse light into its component colors. What causes this dispersion?
A.
Refraction
B.
Reflection
C.
Diffraction
D.
Absorption
Show Answer & Explanation
Correct Answer: A
Dispersion occurs due to refraction, where different wavelengths of light bend at different angles as they pass through the prism.
Q7
Medium
What type of lens is used to correct nearsightedness?
A.
Concave lens
B.
Convex lens
C.
Bifocal lens
D.
Cylinder lens
Show Answer & Explanation
Correct Answer: A
A concave lens diverges light rays, allowing the image to focus on the retina for a person with nearsightedness.
Q8
Hard
A beam of light travels through a medium with a refractive index of 1.5 and enters a second medium with a refractive index of 2.0. If the angle of incidence in the first medium is 30 degrees, what will be the angle of refraction in the second medium?
A.
22 degrees
B.
29 degrees
C.
36 degrees
D.
42 degrees
Show Answer & Explanation
Correct Answer: A
Using Snell's Law, n1 * sin(theta1) = n2 * sin(theta2), where theta1 is 30 degrees. First, we find the angle of refraction in the first medium, then apply it in the second medium's refractive index. The calculation gives approximately 22 degrees.
Q9
Hard
A converging lens has a focal length of 10 cm. An object is placed 30 cm from the lens. What is the distance of the image from the lens?
A.
7.5 cm
B.
15 cm
C.
20 cm
D.
25 cm
Show Answer & Explanation
Correct Answer: C
Using the lens formula (1/f = 1/v - 1/u), where f = 10 cm and u = -30 cm (object distance is taken as negative), solving gives v = 20 cm, indicating the image distance.
Q10
Hard
A lens forms a real image of an object located 30 cm from the lens. If the image distance is 15 cm, what is the focal length of the lens?
A.
10 cm
B.
5 cm
C.
20 cm
D.
25 cm
Show Answer & Explanation
Correct Answer: C
Using the lens formula: 1/f = 1/v - 1/u. Here, v = 15 cm (image distance), u = -30 cm (object distance). Substituting gives 1/f = 1/15 - 1/(-30) = 1/15 + 1/30. Solving this yields f = 20 cm.
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Light — WAEC (West Africa) WAEC Physics Practice Questions Online
This page contains 135 practice MCQs for the chapter Light in WAEC (West Africa) WAEC Physics. The questions are organized by difficulty — 42 easy, 71 medium, 22 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.