Ray Optics and Optical Test

Result

Ray Optics and Optical Test - 40

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

When pencil is dipped in the water, it appears to be bent. Which phenomena is behind this?

A
Reflection

B
Refraction

C
Deflection

D
Rarefaction

Solution

A pencil looks bent in water because of a phenomenon called refraction. When light enters water, it cannot move as fast as it does in air. As light enters water at an angle, it bends away from its original path, and this makes the image look bent.
Question 2
1 / -0

Why does we observe that when stick is kept in water then it appears to be bend under water?

A
Light bends while travelling from one medium to another

B
Light doesn't bend while travelling from one medium to another

C
Light move upward while travelling from one medium to another

D
Light move downward while travelling from one medium to another

Solution

The light as we know needs a medium for its propagation. Every medium has its own refractive index which is usually taken with respect to air. For sake of simplicity the refractive index of air is taken as unity.
When we see any object, the light from that object travels through medium of air and reaches to our retina. The light has its specific wavelength and speed during its propagation.
When an object is placed such that it is in two medium, the light travels from both the media before reaching our eye.
Here the two media are air and water. Water has higher refractive index than air which causes refraction. Due to the change in medium the speed of light decreases. The refraction causes difference in speed of light the stick kept in water appears to be bent or broken.
Question 3
1 / -0

Where should the object be placed to get the virtual image in case of convex lens?

A
Object should be placed between F and 2F

B
Object should be placed between F and O

C
Object should be placed beyond 2F

D
Object should be placed at O

Solution

Correct answer is (b).

When the object is located at a location in front of the focal point, i.e. between F and O, then virtual image is formed by convex lens and the image is located behind the object and is enlarged; in other words, the image dimensions are greater than the object dimensions.
Question 4
1 / -0

Which of the below is one of the laws of refraction?

A
The incident ray, the normal and the refracted ray, all lie in a different plane.

B
The incident ray, the normal and the refracted ray, all lie in the same plane.

C
The incident ray, the normal and the refracted ray, all lie in opposite plane.

D
The incident ray and the refracted ray, both lie in a plane.

Solution

$$\text{The incident ray, the normal and the refracted ray, all lie in the same plane}$$ - is one of the laws of refraction.
Question 5
1 / -0

Which of the following signifies Snell's law?

A
$$ \dfrac {sin \ i}{ sin\ r}= constant $$

B
$$ \dfrac {sin \ r}{ sin\ i}= constant $$

C
$$ sin \ i + sin \ r = Constant$$

D
none of the above

Solution

Snell's law state that the ratio of sine of angle of incidence to the sine of angle of refraction is a constant, for the light of a given colour and for the given pair of media.
$$ \dfrac {sin \ i}{ sin\ r}= constant $$
Question 6
1 / -0

Where should the object be placed if we use convex lens to obtain real, inverted and diminished image?

A
Object should be placed at focal point

B
Object should be placed at finite distance from Focal point

C
Object should be placed at infinity

D
Object should be placed between F and 2F

Solution

Correct answer (c)
Object should be placed at infinity to obtain real, inverted and diminished image in case of convex lens. A real image is an image formed by actual rays of light. these images are always inverted, and they may be either larger or smaller than the object.
Question 7
1 / -0

When is the virtual image formed?

A
when the rays of light after reflection or refraction appear to meet at a point

B
when the rays of light after reflection or refraction meet at a point

C
when the rays of light after deflection appear to meet at a point

D
when the lens rays after reflection or refraction meet at a point

Solution

Correct answer (a)
Virtual image is formed when the rays of light after reflection or refraction appear to meet at a point.If light rays, after reflection or refraction, actually meets at a point then real image is formed and if they appears to meet virtual image is formed.
For example if a ray of light from the object, parallel to the principal axis, when passes through a concave lens seem to be coming out of its focus but do not actually meet.Hence a virtual image is formed.
Question 8
1 / -0

What is refraction?

A
Phenomenon in which ray of light deviates from its path at the surface of separation of two media.

B
Phenomenon in which ray of light reflects from its path at the surface of separation of two media.

C
Phenomenon in which ray of light deviates from its path at the surface of 1st media

D
None

Solution
Question 9
1 / -0

The refractive index of water and glass with respect to air is $$1.3$$ and $$1.5$$ respectively. Then the refractive index of glass with respect to water is

A
$$\dfrac{2.6}{1.5}$$

B
$$\dfrac{1.5}{2.6}$$

C
$$\dfrac{1.3}{1.5}$$

D
$$\dfrac{1.5}{1.3}$$

Solution

As we know,
$$_w\mu_g =\dfrac {_a\mu_g}{_a\mu_w}=\dfrac {1.5}{1.3}$$
Question 10
1 / -0

A ray of light incident on the interface of the medium $$A$$ and $$B$$ and it passes through medium $$B$$ as shown in above figure. Choose the correct option.

A
Medium 1 is more dense than medium 2

B
Medium 1 less dense than medium 2

C
The speed of the light in medium 1 is greater than the speed of the light in medium 2

D
The frequency of the light in medium 1 is greater than the frequency of the light in medium 2

E
The wavelength is the same in medium 1 and medium 2

Solution

When a light ray travels from a rarer medium to denser medium, then the refracted ray bends towards the normal whereas when it travels from denser to rarer medium, then the refracted ray bends away from the normal.
According to the figure, the refracted ray bends away from the normal.
It means it goes from denser to rarer.
Hence medium 1 is more dense than the medium 2.