Angle of incidence on the water film:
When a light ray travels from one medium to another, it undergoes refraction, which is the bending of the ray due to the change in speed. The angle of incidence, denoted by 'i', is the angle between the incident ray and the normal to the surface at the point of incidence.

In this case, the light ray is incident on the water film from air at an angle of 60 degrees. Therefore, the angle of incidence on the water film is 60 degrees.

Refraction of light at the water-air interface:
The refractive index of a medium is a measure of how much the speed of light is reduced when it travels through that medium. It is denoted by 'n' and can be calculated using the formula:

n = speed of light in vacuum / speed of light in the medium

The refractive index of water is 4/3, which means that light travels 4/3 times slower in water compared to vacuum.

When light travels from a medium with a lower refractive index to a medium with a higher refractive index, it bends towards the normal. In this case, the light ray is traveling from air (refractive index = 1) to water (refractive index = 4/3). Therefore, the light ray will bend towards the normal at the water-air interface.

Angle of incidence on the glass block:
Now, we need to find the angle of incidence on the glass block. The refractive index of glass is given as 1.5.

Using Snell's law, which states that the ratio of the sines of the angles of incidence and refraction is equal to the ratio of the refractive indices of the two media:

n1*sin(i1) = n2*sin(i2)

where n1 and n2 are the refractive indices of the first and second media, and i1 and i2 are the angles of incidence and refraction, respectively.

In this case, n1 = 4/3 (refractive index of water), n2 = 1.5 (refractive index of glass), and i1 = 60 degrees (angle of incidence on the water film).

Let's calculate the angle of refraction using Snell's law:

(4/3)*sin(60) = 1.5*sin(i2)

Simplifying the equation:

sin(60) = (1.5*sin(i2))/(4/3)

sin(60) = (1.5*sin(i2))*(3/4)

√(3)/2 = (1.5*sin(i2))*(3/4)

√(3)/2 = (9/8)*sin(i2)

sin(i2) = (√(3)/2)*(8/9)

sin(i2) = 4√(3)/9

i2 = sin^(-1)(4√(3)/9)

Using a calculator, i2 is approximately 53.13 degrees.

Therefore, the angle of incidence on the glass block is approximately 53.13 degrees.