Answer:
(a) 
(b) 1.71
Explanation:
(a) The difference in the times of travel in the two case = 
This difference is the time in the transparent material. With a thickness of 35.0 cm, the speed in the material is

(b) The refractive index of the material is the ratio of the velocity of light in vacuum to its velocity in the material. Using speed of light in vacuum as
, the refractive index,
, is

Answer:
a) Watt is a derived unit because it's not a “base unit.”
b) The atomic clock is suitable for measuring time because natural atomic oscillations happen at a higher frequency and as a result they are more stable.
c) There is fluctuation in time measured by a pendulum clock because the pendulum rod changes in length slightly with changes in temperature, causing changes in the rate of the clock. An increase in temperature causes the rod to expand, making the pendulum longer, so its period increases and the clock loses time.
D) The weight of an object is more at pole and less at equator of the earth because the distance of the pole is less than the distance of the equator from the centre of the earth.
e) The weight of an object on the moon is about one-sixth the weight it would have on the earth because the moon's gravitation force is determined by the mass and the size of the moon. Hence, the weight of an object on the moon is 1/6th its weight on the earth.
Answer:
Angle of diffraction for second order maxima is θ = 18.941°
Explanation:
From the question it is given that
wavelength of incident light = λ = 541 nm = 541 x 
order of maxima = n =2
diffraction grating has 600 lines per mm
⇒ distance between two slit is
= 1.66 x
m
using the relation of Braggs diffraction formula i.e.,
2dsinθ = nλ ..................................(1)
where, d = distance between two lines of grating
θ is the angle of diffraction
n= order of maxima
λ is the intensity of incident photon
on substituting the respected values in relation (1) we get,
2 x 1.66 x
m sinθ = 2 x 541 x 
⇒ sinθ = 0.3246
⇒ θ =
= 18.941 °