21. Rainbow formation is a natural phenomenon illustrating that white light
- A. splits into three components after rainfall
- B. is dispersed by glass prisms
- C. splits into its constituent colours before rainfall
- D. is dispersed into its constituent colours after rainfall
Correct Option: Answer is D
22.
The lens illustrated above can best be described as a
- A. converging meniscus
- B. plano-convex
- C. diverging meniscus
- D. bi-convex
Correct Option: Answer is B
The diagram is that of a plano-convex lens; a type of converging lens
23. Two plane mirrors are inclined to each other such that an object placed between them has 11 images. Determine the angle of inclination
- A. 30°
- B. 45°
- C. 60°
- D. 90°
Correct Option: Answer is A
Formula for number of images = \(\frac{360}{n} – 1\)
where n is the angle of inclination.
Given the number of images = 11, we have
\(\frac{360}{n} – 1 = 11\)
\(\frac{360}{n} = 12\)
\(n = \frac{360}{12} =30°\)
24. The pitch of a note is not affected by
- A. frequency
- B. tension in a vibrating string
- C. mass of a vibrating string
- D. amplitude of sound wave
Correct Option: Answer is D
25. When two flat plate conductors are arranged in such a way that they possess equal and opposite charges seperated by a dielectric, they form a/an
- A. electroscope
- B. electrophorus
- C. capacitor
- D. cell
Correct Option: Answer is C
Most capacitors contain at least two electrical conductors often in the form of metallic plates or surfaces separated by a dielectric medium.
26.
Which electrical device is illustrated above?
- A. a.c. generator
- B. a.c. motor
- C. d.c. generator
- D. d.c. motor
Correct Option: Answer is C
27. A simple barometer is constructed using a liquid Q1 of density 16.2g/cm³. Calculate the least lenth of the tube to be used to measure pressure of 1.5atm. [Density of mercury = 13.6g/cm³, 1atm = 76.0 cm of Mercury]
- A. 1358mm
- B. 957mm
- C. 760mm
- D. 638mm
Correct Option: Answer is D
Let \(h_{Q}\) and \(\rho_{Q}\) be the least length and the density of \(Q_{1}\)
while \(h\) and \(\rho\) are the length and density of mercury respectively.
\(h\times \rho \times g = h_{Q} \times \rho_{Q} \times g\)
\(76cm \times 13.6 \times 10 = h_{Q} \times 16.2 \times 10\)
\(h_{Q} = \frac{76\times13.6\times10}{16.2\times10}\)
\(h_{Q} = \frac{10336}{162}\)
\(h_{Q} \approxeq 63.8cm = 638mm\)
28.
The diagram above illustrates the mercury-in-glass thermometer used for determining the temperature of a room. Use the data on it to determine the room temperature.
- A. 3.3°C
- B. 7.0°C
- C. 13°C
- D. 30.0°C
Correct Option: Answer is C
29. To obtain a virtual, erect and magnified image from a thin converging lens, an object must be placed
- A. between the focus and the lens
- B. at the focus
- C. between the focal length and twice the focal length
- D. beyond twice the focal length
Correct Option: Answer is A
When the object is placed between the optical centre of the lens and the focal length, the image formed is virtual, erect and magnified.
30.
The diagram above represents a transverse travelling wave. Which two points are 180° out of phase?
- A. A and E
- B. B and D
- C. C and F
- D. D and H