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PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364953 A boat has green light of wavelength $λ = 500 n m$ on the mast. What wavelength would be measured and what colour would be observed for this light as seen by a driver submerged in water by the side of the boat?
Given $n_{w} = \frac{4}{3}$

1 Green of wavelength

375 n m

2

665 n m

3 Green of waelength

500 n m

4 Blue of wavelength

375 n m

Explanation:

Here, $n_{w} = \frac{4}{3}, λ_{a} = 500 n m$
As $n_{w} = \frac{λ_{a}}{λ_{w}}$ ,
[subscripts $a$ and $w$ for air and water respectively]
$∴ λ_{w} = \frac{500 n m}{(4 / 3)} = 375 n m$
Colour of light is determined by its frequency and not by its wavelength. As frequency does not change on refraction, colour will not change and will remain green.

KCET - 2010

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364954 Total internal reflection takes place

1 when a ray moves from denser to rarer and incident angle is greater than critical angle

2 when a ray moves from rarer to denser and incident angle is less than critical angle

3 when a ray moves from rarer to denser and incident angle is equal to critical angle

4 None of the above

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364955 Assertion :
Endoscopy involves use of optical fibres to study internal organs.
Reason :
Optical fibres are based on phenomenon of total internal reflection.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

AIIMS - 2009

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364956 A fish looking up through the water sees the outside world, contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is $12 c m$ below the water surface, the radius of this circle in $c m$ is

1

36 \sqrt{7}

2

\frac{36}{\sqrt{7}}

3

36 \sqrt{5}

4

4 \sqrt{5}

Explanation:

The situtaiton is shown in figure
supporting img
$\begin{aligned} \sin θ_{C} = \frac{1}{μ} \Rightarrow \tan θ_{C} = \frac{A B}{A O} (\Rightarrow \sin θ_{c} = \frac{3}{4}) \\ \Rightarrow A B = O A \tan θ_{C} \end{aligned}$
$\begin{matrix} A B = \frac{O A}{\sqrt{μ^{2} - 1}} = \frac{12}{\sqrt{{(\frac{4}{3})}^{2} - 1}} = \frac{36}{\sqrt{7}} \\ [∴ \tan θ_{C} = \frac{1}{\sqrt{μ^{2} - 1}}] \end{matrix}$

AIIMS - 2008

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364957 In optical fibres, the refractive index of the core is

1 greater than that of the cladding

2 equal to that of the cladding

3 smaller than that of the cladding

4 independent of that of the cladding

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364953 A boat has green light of wavelength $λ = 500 n m$ on the mast. What wavelength would be measured and what colour would be observed for this light as seen by a driver submerged in water by the side of the boat?
Given $n_{w} = \frac{4}{3}$

1 Green of wavelength

375 n m

2

665 n m

3 Green of waelength

500 n m

4 Blue of wavelength

375 n m

Explanation:

Here, $n_{w} = \frac{4}{3}, λ_{a} = 500 n m$
As $n_{w} = \frac{λ_{a}}{λ_{w}}$ ,
[subscripts $a$ and $w$ for air and water respectively]
$∴ λ_{w} = \frac{500 n m}{(4 / 3)} = 375 n m$
Colour of light is determined by its frequency and not by its wavelength. As frequency does not change on refraction, colour will not change and will remain green.

KCET - 2010

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364954 Total internal reflection takes place

1 when a ray moves from denser to rarer and incident angle is greater than critical angle

2 when a ray moves from rarer to denser and incident angle is less than critical angle

3 when a ray moves from rarer to denser and incident angle is equal to critical angle

4 None of the above

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364955 Assertion :
Endoscopy involves use of optical fibres to study internal organs.
Reason :
Optical fibres are based on phenomenon of total internal reflection.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

AIIMS - 2009

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364956 A fish looking up through the water sees the outside world, contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is $12 c m$ below the water surface, the radius of this circle in $c m$ is

1

36 \sqrt{7}

2

\frac{36}{\sqrt{7}}

3

36 \sqrt{5}

4

4 \sqrt{5}

Explanation:

The situtaiton is shown in figure
supporting img
$\begin{aligned} \sin θ_{C} = \frac{1}{μ} \Rightarrow \tan θ_{C} = \frac{A B}{A O} (\Rightarrow \sin θ_{c} = \frac{3}{4}) \\ \Rightarrow A B = O A \tan θ_{C} \end{aligned}$
$\begin{matrix} A B = \frac{O A}{\sqrt{μ^{2} - 1}} = \frac{12}{\sqrt{{(\frac{4}{3})}^{2} - 1}} = \frac{36}{\sqrt{7}} \\ [∴ \tan θ_{C} = \frac{1}{\sqrt{μ^{2} - 1}}] \end{matrix}$

AIIMS - 2008

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364957 In optical fibres, the refractive index of the core is

1 greater than that of the cladding

2 equal to that of the cladding

3 smaller than that of the cladding

4 independent of that of the cladding

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364953 A boat has green light of wavelength $λ = 500 n m$ on the mast. What wavelength would be measured and what colour would be observed for this light as seen by a driver submerged in water by the side of the boat?
Given $n_{w} = \frac{4}{3}$

1 Green of wavelength

375 n m

2

665 n m

3 Green of waelength

500 n m

4 Blue of wavelength

375 n m

Explanation:

Here, $n_{w} = \frac{4}{3}, λ_{a} = 500 n m$
As $n_{w} = \frac{λ_{a}}{λ_{w}}$ ,
[subscripts $a$ and $w$ for air and water respectively]
$∴ λ_{w} = \frac{500 n m}{(4 / 3)} = 375 n m$
Colour of light is determined by its frequency and not by its wavelength. As frequency does not change on refraction, colour will not change and will remain green.

KCET - 2010

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364954 Total internal reflection takes place

1 when a ray moves from denser to rarer and incident angle is greater than critical angle

2 when a ray moves from rarer to denser and incident angle is less than critical angle

3 when a ray moves from rarer to denser and incident angle is equal to critical angle

4 None of the above

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364955 Assertion :
Endoscopy involves use of optical fibres to study internal organs.
Reason :
Optical fibres are based on phenomenon of total internal reflection.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

AIIMS - 2009

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364956 A fish looking up through the water sees the outside world, contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is $12 c m$ below the water surface, the radius of this circle in $c m$ is

1

36 \sqrt{7}

2

\frac{36}{\sqrt{7}}

3

36 \sqrt{5}

4

4 \sqrt{5}

Explanation:

The situtaiton is shown in figure
supporting img
$\begin{aligned} \sin θ_{C} = \frac{1}{μ} \Rightarrow \tan θ_{C} = \frac{A B}{A O} (\Rightarrow \sin θ_{c} = \frac{3}{4}) \\ \Rightarrow A B = O A \tan θ_{C} \end{aligned}$
$\begin{matrix} A B = \frac{O A}{\sqrt{μ^{2} - 1}} = \frac{12}{\sqrt{{(\frac{4}{3})}^{2} - 1}} = \frac{36}{\sqrt{7}} \\ [∴ \tan θ_{C} = \frac{1}{\sqrt{μ^{2} - 1}}] \end{matrix}$

AIIMS - 2008

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364957 In optical fibres, the refractive index of the core is

1 greater than that of the cladding

2 equal to that of the cladding

3 smaller than that of the cladding

4 independent of that of the cladding

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364953 A boat has green light of wavelength $λ = 500 n m$ on the mast. What wavelength would be measured and what colour would be observed for this light as seen by a driver submerged in water by the side of the boat?
Given $n_{w} = \frac{4}{3}$

1 Green of wavelength

375 n m

2

665 n m

3 Green of waelength

500 n m

4 Blue of wavelength

375 n m

Explanation:

Here, $n_{w} = \frac{4}{3}, λ_{a} = 500 n m$
As $n_{w} = \frac{λ_{a}}{λ_{w}}$ ,
[subscripts $a$ and $w$ for air and water respectively]
$∴ λ_{w} = \frac{500 n m}{(4 / 3)} = 375 n m$
Colour of light is determined by its frequency and not by its wavelength. As frequency does not change on refraction, colour will not change and will remain green.

KCET - 2010

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364954 Total internal reflection takes place

1 when a ray moves from denser to rarer and incident angle is greater than critical angle

2 when a ray moves from rarer to denser and incident angle is less than critical angle

3 when a ray moves from rarer to denser and incident angle is equal to critical angle

4 None of the above

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364955 Assertion :
Endoscopy involves use of optical fibres to study internal organs.
Reason :
Optical fibres are based on phenomenon of total internal reflection.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

AIIMS - 2009

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364956 A fish looking up through the water sees the outside world, contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is $12 c m$ below the water surface, the radius of this circle in $c m$ is

1

36 \sqrt{7}

2

\frac{36}{\sqrt{7}}

3

36 \sqrt{5}

4

4 \sqrt{5}

Explanation:

The situtaiton is shown in figure
supporting img
$\begin{aligned} \sin θ_{C} = \frac{1}{μ} \Rightarrow \tan θ_{C} = \frac{A B}{A O} (\Rightarrow \sin θ_{c} = \frac{3}{4}) \\ \Rightarrow A B = O A \tan θ_{C} \end{aligned}$
$\begin{matrix} A B = \frac{O A}{\sqrt{μ^{2} - 1}} = \frac{12}{\sqrt{{(\frac{4}{3})}^{2} - 1}} = \frac{36}{\sqrt{7}} \\ [∴ \tan θ_{C} = \frac{1}{\sqrt{μ^{2} - 1}}] \end{matrix}$

AIIMS - 2008

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364957 In optical fibres, the refractive index of the core is

1 greater than that of the cladding

2 equal to that of the cladding

3 smaller than that of the cladding

4 independent of that of the cladding

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364953 A boat has green light of wavelength $λ = 500 n m$ on the mast. What wavelength would be measured and what colour would be observed for this light as seen by a driver submerged in water by the side of the boat?
Given $n_{w} = \frac{4}{3}$

1 Green of wavelength

375 n m

2

665 n m

3 Green of waelength

500 n m

4 Blue of wavelength

375 n m

Explanation:

Here, $n_{w} = \frac{4}{3}, λ_{a} = 500 n m$
As $n_{w} = \frac{λ_{a}}{λ_{w}}$ ,
[subscripts $a$ and $w$ for air and water respectively]
$∴ λ_{w} = \frac{500 n m}{(4 / 3)} = 375 n m$
Colour of light is determined by its frequency and not by its wavelength. As frequency does not change on refraction, colour will not change and will remain green.

KCET - 2010

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364954 Total internal reflection takes place

1 when a ray moves from denser to rarer and incident angle is greater than critical angle

2 when a ray moves from rarer to denser and incident angle is less than critical angle

3 when a ray moves from rarer to denser and incident angle is equal to critical angle

4 None of the above

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364955 Assertion :
Endoscopy involves use of optical fibres to study internal organs.
Reason :
Optical fibres are based on phenomenon of total internal reflection.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

AIIMS - 2009

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364956 A fish looking up through the water sees the outside world, contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is $12 c m$ below the water surface, the radius of this circle in $c m$ is

1

36 \sqrt{7}

2

\frac{36}{\sqrt{7}}

3

36 \sqrt{5}

4

4 \sqrt{5}

Explanation:

The situtaiton is shown in figure
supporting img
$\begin{aligned} \sin θ_{C} = \frac{1}{μ} \Rightarrow \tan θ_{C} = \frac{A B}{A O} (\Rightarrow \sin θ_{c} = \frac{3}{4}) \\ \Rightarrow A B = O A \tan θ_{C} \end{aligned}$
$\begin{matrix} A B = \frac{O A}{\sqrt{μ^{2} - 1}} = \frac{12}{\sqrt{{(\frac{4}{3})}^{2} - 1}} = \frac{36}{\sqrt{7}} \\ [∴ \tan θ_{C} = \frac{1}{\sqrt{μ^{2} - 1}}] \end{matrix}$

AIIMS - 2008

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364957 In optical fibres, the refractive index of the core is

1 greater than that of the cladding

2 equal to that of the cladding

3 smaller than that of the cladding

4 independent of that of the cladding

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