5.3cm
3.2cm
2.7cm
1.6cm
Correct answer is B
v = 4u, if u = 2cm, v = 8cm
F = \(\frac{uv}{u + v}\)
= \(\frac{2 \times 8}{2 + 8}\)
= 1.6cm
r = 2F
= 2 x 1.6
= 3.2cm
If the refractive index of glass is 1.5, what is the critical angle at the air-glass interface?
sin-1\(\frac{1}{2}\)
sin-1\(\frac{2}{3}\)
sin-1\(\frac{3}{4}\)
sin-1\(\frac{8}{9}\)
Correct answer is B
sin ic \(\frac{1}{n}\) = \(\frac{1}{1 - 5}\)
i = sin-1\(\frac{1}{1 - 5}\)
= sin-1\(\frac{10}{15}\)
= sin-1\(\frac{2}{3}\)
In which of the following arrangements is the wavelength in an increasing order?
Gamma rays, infra-red rays, x-rays, radiowaves
Gamma rays, x-rays, infra-red ray, radiowaves
Radiowaves, x-rays, gamma ray, infra-red rays
Infra-red rays, radiowaves, x-rays, gamma rays
Correct answer is B
No explanation has been provided for this answer.
8.0cm
16.0cm
24.0cm
32.0cm
Correct answer is D
F = 12cm, V = 3u
F = \(\frac{uv}{u + v}\)
12 = \(\frac{u\times 3u}{u + 3v}\)
u = 16cm, and v = 48cm
therefore, distance between u and v
v = 48 - 16 = 32cm
Which of the following is true of sounds?
sound travels faster in air at 20oC than at 30oC
the frequency of a given sound wave changes when it crosses the boundary seperating two media
the wavelength of a given sound wave in air decreases as the temperature increases
sound waves cannot be reflected
Correct answer is C
No explanation has been provided for this answer.