1.
If an incident ray passes through the focus of the concave mirror the reflected ray will?
Correct Answer
B. Parallel to the principal axis
Explanation
When an incident ray passes through the focus of a concave mirror, it will be reflected parallel to the principal axis. This is because the focus is a special point on the principal axis where all rays parallel to the principal axis converge after reflection. Therefore, when the incident ray passes through the focus, it is already parallel to the principal axis and will continue to be so after reflection.
2.
The refractive index of ice, salt & glass is 1.31 1.54, and 1.52 respectively which light travels faster and slower.
Correct Answer
C. Ice and salt
Explanation
The refractive index of a material determines how much light slows down when it enters that material. A higher refractive index means that light travels slower in that material compared to a material with a lower refractive index. In this case, the refractive index of ice is 1.31 and the refractive index of salt is 1.54. Since the refractive index of salt is higher than that of ice, light would travel slower in salt compared to ice. Therefore, the correct answer is "Ice and salt".
3.
Power of a lens is reciprocal of?
Correct Answer
C. Focal length
Explanation
The power of a lens is defined as the reciprocal of its focal length. The focal length of a lens is the distance between the lens and its focal point, where parallel rays of light converge or appear to diverge from. The power of a lens determines its ability to converge or diverge light rays, and it is measured in units called diopters. Therefore, the correct answer is focal length.
4.
When the object is placed between f and 2f of a convex lens the image formed is?
Correct Answer
C. Beyond 2f on the other side
Explanation
When an object is placed between the focal point (f) and twice the focal point (2f) of a convex lens, the image formed is located beyond 2f on the other side. This is because in this position, the image formed by the lens is real, inverted, and magnified. The distance between the object and the lens is less than the focal length, causing the image to be formed on the opposite side of the lens and beyond 2f.
5.
A Ray of light traveling from a rarer medium to a denser medium.
Correct Answer
B. Bend towards normal
Explanation
When a ray of light travels from a rarer medium to a denser medium, it slows down and changes direction. This change in direction is known as refraction. The ray of light bends towards the normal, which is an imaginary line perpendicular to the interface between the two mediums. This is because the speed of light is slower in the denser medium, causing the light to change its path and move closer to the normal. Therefore, the correct answer is "Bend towards normal."
6.
A student does the experiment on tracing the path of a ray of light passing through a rectangular glass slab for different angles of incidence. He can get a correct measure of the angle of incidence and the angle of emergence by following the labeling indicated in figure:
Correct Answer
A. IV
Explanation
The correct answer is IV because it is labeled as the angle of incidence. The angle of incidence is the angle between the incident ray and the normal to the surface of the slab.
7.
The image formed by the plane mirror is:
Correct Answer
C. Virtual and erected
Explanation
The image formed by a plane mirror is virtual because it cannot be projected onto a screen. It is also erected because it appears upright, maintaining the same orientation as the object. In a plane mirror, light rays reflect off the mirror surface, creating an image that appears to be behind the mirror. However, this image cannot be projected onto a screen and is therefore virtual.
8.
A concave mirror gives the real inverted and same size of the image and object is placed.
Correct Answer
C. At C
Explanation
A concave mirror gives a real, inverted, and same-sized image when the object is placed at the center of curvature (C). This is because the center of curvature is the focal point of the mirror, where parallel rays of light converge after reflection. As a result, the image formed at C is real (can be projected onto a screen), inverted (upside down), and same-sized as the object.
9.
The radius of curvature 200 CM it's focal length is:
Correct Answer
B. 1 metre
Explanation
The focal length of a lens is equal to half of its radius of curvature. In this case, the radius of curvature is given as 200 cm. Therefore, the focal length would be half of 200 cm, which is equal to 100 cm or 1 meter.
10.
What happens to the speed of light when it goes from air into a denser medium like glass?
Correct Answer
C. The speed of light decreases
Explanation
The correct answer is C. When light passes from a less dense medium (such as air) into a denser medium (such as glass or water), it slows down because it interacts more with the particles in the denser medium, causing refraction.
11.
The focal length of a lens or a mirror or lens is always half of the length of the radius of curvature.
Correct Answer
A. True
Explanation
The focal length of a lens or a mirror is determined by the curvature of the surface. The radius of curvature is the distance between the center of curvature and the lens or mirror. The focal length is defined as the distance between the focal point and the lens or mirror. By definition, the focal length is always half of the radius of curvature. Therefore, the statement is true.
12.
Which of them is not paired correctly
1. Solar furnace -concave mirror
2.Rear​​​Rear view mirror -convex mirror
3. Magnifying glass -convex lens
4. Shaving mirror - convex mirror
Correct Answer
C. 4
Explanation
The correct answer is 4. A shaving mirror is not paired correctly with a convex mirror. A shaving mirror is actually paired with a concave mirror. A concave mirror is used in a shaving mirror to magnify the reflection and allow for a closer, more detailed view of the face while shaving.
13.
Bending of light is called?
Correct Answer
D. Refraction
Explanation
Refraction is the correct answer because it refers to the bending of light as it passes through different mediums, such as air, water, or glass. This bending occurs due to the change in speed of light when it enters a different medium, causing the light to change direction.
14.
The angle of incidence for a Ray of light having 0 reflection angle is:
Correct Answer
A. 0°
Explanation
The angle of incidence for a ray of light having 0 reflection angle is 0°. This means that the ray of light is incident perpendicular to the surface it is hitting. When the angle of reflection is 0°, it indicates that the ray of light is not reflected at all and instead passes straight through the surface. This can occur when the ray of light is incident on a surface with the same refractive index as the medium it is coming from, causing no change in direction.
15.
The speed of the light in water is 2.5X10 power 8 metres per second if the speed of the lit in a vacuum is 3 X 10 power 8 metres per second. Calculate the refractive index of it travels From water to vacuum.
Correct Answer
1.2
Explanation
The refractive index is calculated by dividing the speed of light in a vacuum by the speed of light in the medium. In this case, the speed of light in a vacuum is given as 3 X 10^8 m/s and the speed of light in water is given as 2.5 X 10^8 m/s. Dividing these two values gives a refractive index of 1.2.
16.
The laws of reflection hold good for?
Correct Answer
D. All the mirror irrespective of their shape
Explanation
The laws of reflection refer to the principles that govern the behavior of light when it reflects off a surface. These laws state that the angle of incidence is equal to the angle of reflection, and that the incident ray, reflected ray, and normal to the surface all lie in the same plane. These laws apply to all mirrors, regardless of their shape. Therefore, the correct answer is that the laws of reflection hold good for all mirrors irrespective of their shape.
17.
Light travels fastest in?
Correct Answer
C. Vacuum
Explanation
Light travels fastest in a vacuum because there are no particles or molecules to slow it down. In other mediums like air, water, and glass, light interacts with the molecules, causing it to slow down. However, in a vacuum, there is no medium for light to interact with, allowing it to travel at its maximum speed of approximately 299,792,458 meters per second.
18.
The image formed by a compound microscope is?
Correct Answer
C. Virtual and enlarged
Explanation
A compound microscope uses a combination of lenses to magnify the image of a small object. The image formed by the compound microscope is virtual because the light rays do not actually converge to form a real image. Instead, the image is formed by the eye looking through the microscope. The image is also enlarged because the magnifying power of the microscope allows for a larger view of the object compared to the naked eye.
19.
Which of them converge parallel light rays incident upon them?
Correct Answer
A. Concave mirror
Explanation
A concave mirror converges parallel light rays incident upon it. This is because a concave mirror is curved inward, causing the rays of light to converge at a focal point. In contrast, a plane mirror reflects light rays without converging or diverging them, and a convex mirror diverges parallel light rays. Therefore, only a concave mirror has the property of converging parallel light rays.
20.
The image formed by the actual reflection of light is?
Correct Answer
D. Real and inverted image
Explanation
When light reflects off a surface, it forms an image. In this case, the correct answer states that the image formed by the actual reflection of light is "real and inverted." This means that the image is formed on the opposite side of the reflecting surface compared to the object, and it is a true representation of the object. The term "inverted" indicates that the top and bottom of the image are flipped compared to the object.
21.
What will be the power of the lens if the focal length is reduced to 1 by 4?
Correct Answer
C. Power of lens increases by four times
Explanation
When the focal length of a lens is reduced to 1/4, it means that the lens becomes more converging, which implies that it has a shorter focal length. The power of a lens is inversely proportional to its focal length, so when the focal length decreases, the power of the lens increases. In this case, since the focal length is reduced to 1/4, the power of the lens increases by four times.
22.
The center of the reflecting surface of a spherical mirror is called?
Correct Answer
A. Pole
Explanation
The center of the reflecting surface of a spherical mirror is called the pole. It is the point where the principal axis intersects the mirror. The pole is an important point in understanding the behavior of light rays when they interact with the mirror. It helps in determining the position and orientation of the image formed by the mirror.
23.
Whenever a Ray of light passes from denser to rarer:
Correct Answer
B. I<r
Explanation
When a ray of light passes from a denser medium to a rarer medium, the angle of incidence (i) is always greater than the angle of refraction (r). This is known as Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the speeds of light in the two media. Since the speed of light is greater in a rarer medium, the angle of refraction is smaller than the angle of incidence. Therefore, i
24.
The following is not the property of the image formed on the plane mirror.
Correct Answer
D. Images real and same size
Explanation
The image formed on a plane mirror is virtual, meaning it cannot be projected onto a screen. It is also laterally inverted, meaning it appears flipped horizontally compared to the object. The image is the same size as the object, as there is no magnification or reduction. However, the image formed on a plane mirror is not real, as it cannot be projected onto a screen or captured on a film.