Optics-2

Vanya is trying to understand how light bends when it passes through different materials. The equation to calculate the refractive index is ______.

• n or μ = c/v

• rμ = l/m

• i = v/l

• μ = v/m

Answer explanation

The correct equation for calculating the refractive index (n or μ) is n or μ = c/v, where c is the speed of light in a vacuum and v is the speed of light in the material. This relationship shows how light bends in different media.

Siya is conducting an experiment to compare the speed of light in different mediums. If the absolute refractive indices of water and glass are 4/3 and 3/2, respectively, then what will be the ratio of velocity of light in water to that in glass?

• 2

• 8/9

• 9/8

• 1/2

Answer explanation

The speed of light in a medium is inversely proportional to its refractive index. For water (n=4/3) and glass (n=3/2), the ratio of velocities is (c/n_water) / (c/n_glass) = (3/4) / (2/3) = 8/9. Thus, the correct answer is 8/9.

Aarush is observing a light beam as it travels from water to air. He wonders when total internal reflection occurs in this scenario. It happens when _______________________________________.

• light passes from a denser to a rarer medium

• light comes into air from vacuum

• light goes to vacuum from air

• light passes from rarer to denser medium

Answer explanation

Total internal reflection occurs when light passes from a denser medium (like water) to a rarer medium (like air). This is because the angle of incidence must exceed the critical angle for reflection to happen.

Eshaan was experimenting with light in his physics class. He learned that for light to travel from an optically denser medium into an optically rarer medium, certain conditions must be met. Specifically, the angle of incidence in the denser medium should be greater than the critical angle for a given pair of media. What principle does this represent?

• Snell's law of reflection

• Snell's law of refraction

• Condition of total internal reflection

• None of the above

Answer explanation

The scenario describes total internal reflection, which occurs when light travels from a denser to a rarer medium at an angle greater than the critical angle, preventing refraction and reflecting all light back into the denser medium.

Naira was observing a beautiful sunset when she noticed a shimmering effect on the horizon. She wondered, what is this phenomenon called?

• refraction of light only

• total internal, reflection of light only

• refraction and total internal reflection of light

• dispersion of light only

Answer explanation

The shimmering effect Naira observed is due to both refraction and total internal reflection of light, which occur when light passes through different mediums, creating beautiful visual phenomena during sunsets.

Anika is conducting an experiment with light and discovers that the critical angle is the angle at which the angle of refraction is ______.

• 0°

• 90°

• 180°

• 45°

Answer explanation

The critical angle is defined as the angle of incidence at which the angle of refraction is 90°. At this angle, light refracts along the boundary, leading to total internal reflection for angles greater than the critical angle.

During a physics experiment, Aarav observed that at the critical angle, the ray instead of being ____________ is totally _______________ back in a denser medium.

• refracted, reflected

• reflected, refracted

• absorbed, reflected

• absorbed, refracted

Answer explanation

At the critical angle, the ray cannot pass into the less dense medium and is instead totally reflected back. Therefore, the correct completion is 'refracted, reflected'.

Aisha is conducting an experiment with light in her physics class. She learns that when a ray of light passes from a denser medium to a rarer medium at an angle greater than the critical angle, it gets totally reflected in a ____________ medium

• denser

• rarer

• Both (A) and (B)

• None of the above

Answer explanation

When light passes from a denser medium to a rarer medium at an angle greater than the critical angle, it undergoes total internal reflection. This occurs within the denser medium, making 'denser' the correct choice.

Sanya is conducting an experiment on light refraction. Which is the correct formula for critical angle?

• ic = sin-1(μ1/μ2)

• ic = sin-1(μ2/μ1)

• ic = sin-1μ

• ic = sin-1(1/μ)

Answer explanation

The critical angle (ic) is determined by the ratio of the refractive indices of the two media. The correct formula is ic = sin-1(μ1/μ2), where μ1 is the refractive index of the first medium and μ2 of the second.

While conducting an experiment, Ishaan noticed that when a beam of light travels through water and hits the surface of glass, it gets reflected. This phenomenon is regarded as _______

• External Reflection

• Internal Reflection

• Both (A) and (B)

• None of the above

Answer explanation

When light travels from water to glass, it reflects at the boundary, which is known as external reflection. Internal reflection occurs within a medium, not at the interface of two different media.