Electromagnetic Waves Unit (Average)

A beam of light was turned on from one end of an L-shaped room. Which of the following will most likely happen to the beam of light?

• The beam of light will hit one of the walls of the L-shaped room.

• The beam of light will reach the other end of the L-shaped room.

• The beam of light will pass through the wall of the L-shaped room.

• The given data is insufficient

Answer explanation

Light travels in a straight path. Upon encountering a barrier or surface, light may bend or bounce off.

In this L-shaped room, light will travel in a straight path and hit the wall right in front of it.

Which of the following best describes the phenomenon of reflection?

• The bending of light waves as they pass from one medium to another with a different refractive index.

• The separation of white light into its component colors due to differences in the speed of light in different media.

• The superposition of two or more waves to produce a resultant wave that is either reinforced or canceled out.

• The bouncing of light waves off a surface at an angle equal to the angle of incidence.

Answer explanation

Reflection is the bouncing of light waves off a surface at an angle equal to the angle of incidence. When light waves encounter a smooth surface, such as a mirror or still water, they bounce back in a predictable way, with the angle of incidence equaling the angle of reflection. This phenomenon is responsible for many optical effects, such as the way we see ourselves in a mirror and the way light behaves when it hits a curved surface.

Refraction, where light waves bend as they pass from one medium to another with a different refractive index.

Dispersion, where white light is separated into its component colors when it passes through a prism or other medium that refracts light differently depending on its wavelength.

Interference, where two or more waves interact to produce a resultant wave that is either reinforced or canceled out, depending on their phase relationship.

These are called optical phenomena.

Which of the following statements is false? 

• A plane mirror causes regular reflection. 

• The normal is the line parallel to a surface. 

• The normal is always perpendicular to a surface. 

• The angle of incidence is always equal to the angle of reflection. 

Answer explanation

Reflection can either be regular or diffuse reflection.

Regular reflection is when parallel incident rays are reflected parallel to each other because the surface is smooth and even.

Diffuse reflection happens when parallel incident rays are reflected in different directions and angles because the surface is not smooth and even.

The diagram on shown is the anatomy of incident rays and reflected rays

Which of the following are the correct values of θ_A and θ_B? 

Given the diagram, which of the following angles represent the angle of reflection? 

• 1

• 2

• 3

• 4

Answer explanation

The angle of incidence is the angle formed between the incident ray and the normal line.

The angle of reflection is the angle formed between the reflected ray and the normal line.

Which of the following diagrams best represents the image formed, represented by the dotted arrow?

• 
• 
• 
• 

Which of the following refers to the change in direction of a wave when it encounters a different medium? 

• Refraction

• Dispersion

• Interference

• Reflection

Answer explanation

Reflection is the bouncing of light waves off a surface at an angle equal to the angle of incidence. When light waves encounter a smooth surface, such as a mirror or still water, they bounce back in a predictable way, with the angle of incidence equaling the angle of reflection. This phenomenon is responsible for many optical effects, such as the way we see ourselves in a mirror and the way light behaves when it hits a curved surface.

Refraction, where light waves bend as they pass from one medium to another with a different refractive index.

Dispersion, where white light is separated into its component colors when it passes through a prism or other medium that refracts light differently depending on its wavelength.

Interference, where two or more waves interact to produce a resultant wave that is either reinforced or canceled out, depending on their phase relationship.

These are called optical phenomena.

Why does refraction occur when light passes from one medium to another?

• Light is absorbed

• Light is reflected

• Light changes in color

• Light changes in speed

Answer explanation

Refraction occurs when light passes from one medium to another because the speed of light changes as it travels through different materials. Light travels at different speeds through different materials because of variations in their refractive indices, which is a measure of how much the speed of light changes as it passes through a material.

Given the diagram, what can be inferred about medium X and medium Y?

• The index of refraction of medium X is equal to the index of refraction of medium Y. 

• The index of refraction of medium X is lower than the index of refraction of medium Y. 

• The index of refraction of medium X is higher than the index of refraction of medium Y. 

• The given data is insufficient. 

Answer explanation

When light passes from one medium to another and bends away from the normal during refraction, it means that the speed of light is increasing as it moves into a medium with a lower refractive index.

The index of refraction is a measure of how much the speed of light is reduced as it passes through a material compared to its speed in a vacuum. When light travels through a material with a higher refractive index, its speed is reduced more than when it travels through a material with a lower refractive index.

The "normal" is an imaginary line that is perpendicular to the surface where the two media meet. When light enters a medium at an angle to the normal, it will bend either towards or away from the normal, depending on the refractive index of the two media.

When light passes from a medium with a higher refractive index to a medium with a lower refractive index, it will bend away from the normal. This is because the speed of light is greater in the first medium, so it slows down when it enters the second medium. As a result, the light waves will bend away from the normal to compensate for the decrease in speed.

Glass has a _____________ index of refraction than air.

• Equal

• Greater

• Less

• Impossible to say

Answer explanation

The index of refraction is a measure of how much the speed of light is reduced as it passes through a material compared to its speed in a vacuum. When light travels through a material with a higher refractive index, its speed is reduced more than when it travels through a material with a lower refractive index.