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WorksheetsVIVA XII OPTICS
Total questions: 40
Worksheet time: 20mins
A person approaches a plane mirror at 5m/s. How fast he approach the mirror image?
5 m/s
2.5 m/s
10 m/s
15 m/s
zero
If the magnification is calculated to be 0.5 in a particular situation, what does that tell you about the image?
It is twice the size of the object.
It tells you nothing about the image.
It is bigger by 0.5
It is 0.5 meters tall
It is half the size of the object.
What type of lens is a Magnifying Glass ?
Convex
Concave
Plane
Plano concave
What is the bending of light rays , due to a change in speed as the rays pass through a substance , called ?
Diffraction
Diffusion
Refraction
Reflection
Interference
If an object is placed at the focus of a concave lens, where is the image formed?
at infinity
at f/2 on the same side of the object
at f/2 on the other side of the object
at F on the other side of the object
If an object is placed at the focus of a convex lens, where is the image formed?
at infinity
at f/2 on the same side of the object
at f/2 on the other side of the object
at F on the other side of the object
Absolute refractive index of a medium is.........
the speed of light in medium to speed of light in the vacuum
the speed of light in medium 1 to speed of light in the medium 2
the speed of light in vacuum to speed of light in the medium
wavelength of light in medium to that in vacuum
What change is expected in the angle of minimum deviation when prism is immersed in water?
increases, as the refractive index of the prism with respect to the medium decreases
decreases, as the refractive index of the prism with respect to the medium decreases
No change
increases, as the refractive index of the prism with respect to the medium increases
decreases, as the refractive index of the prism with respect to the medium increases
What change is expected in the angle of minimum deviation of a prism when red light is replaced by violet light?
increases, as the refractive index of the prism with respect to the medium decreases
decreases, as the refractive index of the prism with respect to the medium decreases
No change
increases, as the refractive index of the prism with respect to the medium increases
decreases, as the refractive index of the prism with respect to the medium increases
Which colour has more deviation when white light is passed through a prism and why?
red, short wavelength and less refractive index
violet, short wavelength and less refractive index
violet, short wavelength and high refractive index
All the colours has the same deviation.
Name the factors that decide angle of minimum deviation of a prism.
Angle of incidence
material of the prism
colour of incident light
medium in which the prism is placed
Why we need a convex lens to find focal length of a concave lens?
it is not compulsory to use a convex lens
concave lens is a converging lens when placed in air
power of concave lens may be less
concave lens will not produce a real image when placed in air
Why we need a convex lens to find focal length of a convex mirror?
it is not compulsory to use a convex lens
convex mirror is a converging mirror
power of convex mirror may be less
convex mirror will not produce a real image.
What is the radius of curvature/ focal length of plane mirror/refracting surface?
10 cm
15 cm
5 cm
infinity
can be any value
convex mirror is not used in/as
telescopes
security purpose
rear view mirror
shaving mirror
dentist
Uses of convex lens
microscopes
telescopes
projectors
correction of hypermetropia
correction of myopia
Name the factors that affect power of a mirror
radius of curvature
refractive index of the medium in which the mirror is placed
refractive index of material of the mirror
colour of incident light
object distance and image distance
Name the factors that affect power of a lens
radius of curvature
refractive index of the medium in which the lens is placed
refractive index of material of the lens
colour of incident light
object distance and image distance
Name the factor s that decide the refractive index of a medium.
angle of incidence
angle of refraction
colour of incident light
nature of the material medium
On Cutting an equi convex lens in to 2 identical plano convex lenses, ..............
focal length becomes half
focal length becomes double
power becomes half
power becomes double
No change in power and focal length
On Cutting a concave mirror in to 2 identical half mirrors, ..............
focal length becomes half
focal length becomes double
power becomes half
power becomes double
No change in power and focal length
Can a convex lens act as a diverging lens in any situation?
No
Yes, when placed in a medium of refractive index lower than that of the lens
Yes, when placed in a medium of refractive index higher than that of the lens
Yes, when placed in a medium of refractive index equal to that of the lens
Can a concave lens act as a converging lens in any situation?
No
Yes, when placed in a medium of refractive index lower than that of the lens
Yes, when placed in a medium of refractive index higher than that of the lens
Yes, when placed in a medium of refractive index equal to that of the lens
Name the colour having maximum speed inside glass prism
Red, as it has longer wavelength
Red, as it has shorter wavelength
Violet, as it has longer wavelength
Violet, as it has shorter wavelength
All the colours have same speed inside glass prism
If a convex/concave lens is placed in a medium such that refractive index of the medium of the lens is same as that of the lens,............
convex lens act as diverging lens
convex lens act as converging lens
concave lens act as diverging lens
concave lens act as converging lens
There will not be any converging or diverging action
What change occur in the power & focal length of a convex lens when immersed in water?
focal length decreases & power decreases
focal length increases & power decreases
focal length decreases & power increases
No change in power and focal length
focal length and power increases
What change occur in the power & focal length of a mirror when immersed in water?
focal length decreases & power decreases
focal length increases & power decreases
focal length decreases & power increases
No change in power and focal length
focal length and power increases
What is the minimum distance between object and its real image for a convex lens?
infinity
2 F
4 F
3 F
2.5 F
Virtual images, ..............
Can be formed on a screen
light rays converges to a point
light rays diverge away
image can not be formed on a screen
always upright
Real images, ..............
Can be formed on a screen
light rays converges to a point
light rays diverge away
image can not be formed on a screen
always inverted
At angle of minimum deviation,..........
angle of incidence = angle of emergence
light rays are parallel to the base of the prism
angle of refraction = half of the angle of the prism
angle of deviation = half of the angle of the prism
Angle of deviation depends on
angle of incidence
angle of the prism
refractive index of the prism
colour of the incident light
A convex lens is placed on the top of a plane mirror such that image and object coincide at the same point at a distance of 12 cm in front of the lens. focal length of the lens = ....
24 cm
12 cm
6 cm
infinity
8 cm
A convex lens and a concave lens of focal length 10 cm is placed in contact. What is the focal length of the combination?
10 cm
20 cm
infinity
5 cm
zero
When the lower half of a convex lens is covered with black paper, ..................
No image is formed
half of the image id formed
complete image is formed but intensity is halved
No change, complete image is formed.
A concave mirror forms an image side by side with an object, with distance from the object to the mirror being 20 cm. Find focal length of the mirror
10 cm
20 cm
5 cm
40 cm
The radius of curvature of each face of a convex lens is same as its focal length, then refractive index of the material of the lens is ................
1.5
2
4/3
1.2
Power of a convex lens is maximum for
red colour as refractive index of glass for red is maximum
violet colour, as refractive index of glass for violet is maximum
Its same for red and violet
violet colour, as refractive index of glass for violet is minimum
red colour as refractive index of glass for red is minimum
Total internal reflection occurs, .............
angle of incidence is greater than critical angle
light travelling from rarer medium to denser medium
light travelling from denser medium to rarer medium
critical angle is greater than angle of incidence
light is incident along the normal
When light is incident on a denser medium, from a rarer medium,
light can bend towards the normal
light can go parallel to the surface of the separation of two media
light may get reflected back to the same medium
light may go straight without any bending
light can bend away from the normal
