Apparent Depth

Q.

What is the intensity of light?

Q.

Define magnifying power of a telescope. Write its expression. A small telescope has an objective lens with a focal length of 150 cm and an eyepiece with a focal length of 5 cm. If this telescope is used to view a 100 m high tower 3 km away, find the height of the final image when it is formed 25 cm away from the eyepiece.

Q.

What is a real life example of diffraction?

Q. A rectangular tank of depth 8 m, is full of water $(\mu =\frac{4}{3})$. The bottom would be seen at the depth of

1. $\frac{8}{3}\text{m}$
2. $8\text{m}$
3. $10\text{m}$
4. $6\text{m}$

Q.

An air bubble in a glass slab $\mu =1.5$ is 5 cm deep when viewed from one face and 2cm deep when viewed from the opposite face. The thickness of the glass slab is

1. 10.5 cm

2. 7 cm

3. 10 cm

4. 7.5 cm

Q. The apparent depth of a needle lying at the bottom of the tank, which is filled with water of refractive index 1.33 to a height of 12.5 cm is measured by a microscope to be 9.4 cm. If water is replaced by a liquid of refractive index 1.63 upto the same height. What distance would the microscope have to be moved to focus on the needle again ?

1. 1.73 cm
2. 2.13 cm
3. 1.5 cm
4. 2.9 cm

Q.

If the relative permeability and dielectric constant of a given medium are equal to $I_r$ and $K$ respectively, then the refractive index of the medium is equal to _____________

1. $\sqrt{I_{r}K}$

2. $\sqrt{I_r{E}_0}$

3. $\sqrt{I_0{E}_0}$

4. $\frac{1}{\sqrt{I_{r}K}}$

Q. A coin placed at the bottom of a vessel, appears to be raised when the vessel is filled with water. This is due to the phenomenon of __________.

1. reflection
2. scattering
3. dispersion
4. refraction

Q.

When a coin placed in a bowl of water and seen from above, it appears:

1. raised from its original position

2. at the same position

3. laterally shifted from its position

4. below its original position

Q. What happens if a incident ray passes straight along the normal through the second medium

Q.

A printed page is kept pressed by a glass cube ($\mu$ = 1.5) of height 6.0 cm. By what amount will the printed letters appear to be shifted when viewed from the top?

1. 2.0 cm

2. 8.0 cm

3. 4.0 cm

4. 6.0 cm

Q.

The speed of light in glass is $2\times {10}^8\frac{m}{s}$ and in the air is $3\times {10}^8\frac{m}{s}$ . An inkdot is covered by a glass plate of $6cm$ thickness. Calculate the shift in the ink dot where it appears to be raised from the original position.

Q.

The bottom of a glass of water appears raised when seen from above

Q. While moving a pic is being screened , a boy introduced a glass slab of thickness 3cm & refractive index 1.5 b/w the projector & the screen . in order to have a clear pic on the screen , the screen shoud be moved through a distance of?? A. 1cm away B. 1cm nearer C. 2cm away D. 3cm away

Q.

A beaker contains water up to a height $h_1$ and K oil above water up to another height $h_2.$ Find the apparent shift in the position of the bottom of the beaker when viewed from above. Refractive index of water is ${\mu }_1$ and that of K.oil is ${\mu }_2.$

1. $(1-\frac{1}{{\mu }_1})h_1+(1-\frac{1}{{\mu }_2})h_2.$

2. $(1-\frac{1}{{\mu }_1})h_1-(1-\frac{1}{{\mu }_2})h_2.$

3. $(1-\frac{1}{{\mu }_1})h_1+(1-\frac{1}{{\mu }_2})h_2.$

4. $(1-\frac{1}{{\mu }_1})h_1-(1-\frac{1}{{\mu }_2})h_2.$

Q.

A diver at a depth of 12m in water ($\mu$ = $\frac{4}{3}$ ) sees the sky in a cone of semi-vertical angle

1. sin^-1 (3/4)
2. sin^-1 (4/3)
3. tan^-1 (4/3)
4. 90°

Q.

Refractive Index of a medium can be calculated as the ratio of real depth and apparent depth.

1. True

2. False

Q. Consider the situation shown in figure. A plane mirror is fixed at a height h above the bottom of a beaker containing water (refractive index $\text{n}$) up to a height $\text{d}$. Find the position of the image of the bottom formed by the mirror.

1. $\text{h - d}+\frac{\text{d}}{\text{n}}$
2. $\text{h + d}+\frac{\text{d}}{\text{n}}$
3. $\text{h - d}-\frac{\text{d}}{\text{n}}$
4. $\text{d}+\frac{\text{d}}{\text{n}}$

Q. When a container is completely filled with water ( n_{​​​​​​w} = 4/3 ) it's bottom appears raised by 4cm. Find the actual depth of water.

Q.

Explain the following :

(a) A coin placed at the bottom of a vessel appears to be raised when water is poured in the vessel.

(b) A straight stick partly dipped in water obliquely, appears to be bent at the surface of water.

(c) The sun is seen before the sunrise and after the sunset.

Q. A plane mirror is placed at the bottom of the tank containing a liquid of refractive index $n$. P is a small object at a height h above the mirror. An observer O-vertically above P outside the liquid see P and its image in the mirror. The apparent distance between these two will be:

1. $2nh$
2. $\frac{2h}{n}$
3. $\frac{2h}{n-1}$
4. $h(1+\frac{1}{n})$

Q. The apparent depth of an air bubble in a glass slab of refractive index $1.5$ is $5cm$ when viewed from one face and $2cm$ when viewed from opposite face. The thickness of glass slab is

1. 10 cm
2. 10.5 cm
3. 7 cm
4. 7.5 cm

Q.

The depth of water in a vessel when seen from air appear to be less because of:

1. reflection of light

2. refraction of light

3. dispersion of light

4. both reflection and dispersion of light

Q. Out of red light and violet light, which will have more lateral displacement?

1. Violet light
2. Red light
3. Both have equal displacement
4. Data insufficient

Q. The apparent depth of a vessel full of water is due to the of light.

1. diffraction
2. refraction
3. dispersion
4. diffusion

Q. A vessel is 2 meter deep .how deep will it appear if it is filled with water and viewed from abov

Q.

Total Internal reflection happens only when light is travelling from an optically denser medium to an optically rarer medium.

1. True
2. False

Q.

If a rectangular tank of depth 8 metre is full of water $\mu =\frac{4}{3}$, then the bottom is seen at a depth of___metres.

Q. As seen from above, the apparent depth of a liquid in a vessel is $15\text{cm}$, when its real depth is $20\text{cm}$. Find the refractive index of the liquid.

1. $1.50$
2. $1.33$
3. $1.25$
4. $1.67$

Q.

How much water should be filled in a container 21 cm in height, so that it appears half filled when viewed from the top of the container (given that ${}^a{\mu }_w=\frac{4}{3}$

1. 8.0 cm

2. 10.5 cm

3. 12.0 cm

4. None of the above