The refractive index for glycerine is

, while for air it is

.
When the light travels from a medium with greater refractive index to a medium with lower refractive index, there is a critical angle over which there is no refraction, but all the light is reflected. This critical angle is given by:

where n1 and n2 are the refractive indices of the two mediums. If we susbtitute the refractive index of glycerine and air in the formula, we find the critical angle for this case:
Question
What is the length of the pipe?
Answer:
(a) 0.52m
(b) f2=640 Hz and f3=960 Hz
(c) 352.9 Hz
Explanation:
For an open pipe, the velocity is given by

Making L the subject then

Where f is the frequency, L is the length, n is harmonic number, v is velocity
Substituting 1 for n, 320 Hz for f and 331 m/s for v then

(b)
The next two harmonics is given by
f2=2fi
f3=3fi
f2=3*320=640 Hz
f3=3*320=960 Hz
Alternatively,
and 

(c)
When v=367 m/s then

Answer:
Angular speed ω=3771.4 rad/min
Revolution=5921 rpm
Explanation:
Given data

To find
Angular speed ω
Revolution per minute N
Solution
First we need to convert the speed of truck to inches per mile
as
1 mile=63360 inches
1 hour=60 minutes
so

Now to solve for angular speed ω by substituting the speed v and radius r in below equation

To solve for N(revolutions per minute) by substituting the angular speed ω in the following equation
Answer:
70509.8039216 N/C
Explanation:
k = Coulomb constant = 
q = Charge = 2.00 µC
l = Length of filament = 5.1 m
r = Radius of cylinder = 10 cm

Electric field is given by

The electric field at the surface of the cylinder is 70509.8039216 N/C