Refraction

Q.

A concave lens is also known as a converging lens.

1. True

2. False

Q. Distinguish between a converging and a diverging lens.

Q.

The virtual image formed by a convex lens is always ________.

1. Diminished
2. Magnified
3. Erect
4. Virtual

Q. What is polarization and diffraction ?

Q.

What happens when a ray of light passes through the optical centre of a lens?

1. no light ray can pass through the optical centre

2. it passes through the lens undeviated.

3. it becomes parallel to principle axis

4. none of the above

Q. What kind of images is formed by the concave lens?
Statement 1: Upright, virtual and smaller than the object.
​Statement 2: Inverted, real and larger than the object.

1. Only Statement 1 is correct

2. Only Statement 2 is correct

3. Both the Statements are correct

4. Both the Statements are wrong

Q. Whaita is the velocity of light in a diamond if the refractive index of diamond with respect to vacuum is $2.5$?

1. $5\times {10}^8$
2. $1.2\times {10}^{10}$
3. $2.5\times {10}^8$
4. $1.2\times {10}^8$

Q.

When a light ray travels from air to glass, where does it bend?

Q.

When light travels obliquely from one medium to another medium, the direction of light rays :

1. changes

2. remains same

3. may change or remain same

4. none of these

Q.

When light goes from an optically rarer to an optically denser medium,

1. angle of incidence > angle of reflection

2. angle of incidence < angle of refraction

3. angle of incidence = angle of refraction

4. angle of incidence > angle of refraction

Q. Define refractive index? Mention its SI unit, if any.

Q.

Total internal reflection of a ray of light is possible when the ($i_c$ = critical angle, $i$ = angle of incidence)

1. Ray goes from denser medium to rarer medium and

2. Ray goes from denser medium to rarer medium and

3. Ray goes from rarer medium to denser medium and

4. Ray goes from rarer medium to denser medium and

Q. The virtual image formed by a concave lens is always ________.

1. Erect
2. Virtual
3. Diminished
4. Magnified

Q. Critical angle for a light ray travelling from denser to rarer medium is defined as the angle of incidence at which the angle of refraction is 90°.
If a ray of light travels from water $\left({\mu }_w\right)$ to air $\left({\mu }_a\right)$. Find the critical angle?

1. ${90}^{\circ }$

2. ${\cos }^{-1}\left(\frac{{\mu }_w}{{\mu }_a}\right)$

3. ${\sin }^{-1}\left(\frac{{\mu }_a}{{\mu }_w}\right)$

4. ${\sin }^{-1}\left(\frac{{\mu }_w}{{\mu }_a}\right)$

Q.

Does refraction of light occur in translucent object

Q. Convex lens does always forms enlarge image?

Q.

We know that light can travel through a vacuum. But are we able to see light when it travels through a vacuum? If not then what is it that makes stars visible in space(which is a vacuum)?

Q.

Describe an experiment to show that a light ray bends when it passes from one transparent medium into another transparent medium.

Q.

A coin is placed at the bottom of a bowl and water is poured into it. The coin appears to be ________ due to _______.

1. lowered, refraction of light

2. raised, refraction of light

3. lowered, reflection of light

4. raised, reflection of light

Q.

When light goes from an optically denser to an optically rarer medium,

1. angle of incidence > angle of refraction

2. angle of incidence = angle of refraction

3. angle of incidence < angle of refraction

4. angle of incidence > angle of reflection

Q.

What is a lens? Write the differences between concave and convex lenses. [5 MARKS]

Q.

Name three important properties of light. [3 MARKS]

Q. The depth of a pond when seen from above appears to be

Q. Refraction and reflection of light takes place on all the objects

Q.

A light ray from air is incident (as shown in figure) at one end of a glass fiber (refractive index $\mu$ = 1.5) making an incidence angle of ${60}^{\circ }$ on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to traverse the straight fiber of length 1 km

1. 6.67 μ sec
2. 5.77 μ sec
3. 3.85 μ sec
4. 3.33 μ sec

Q. The critical angle for water-glass surface is (refractive index of glass = 1.5 and refractive index of water = 4/3)

Q.

Which has a higher refractive index, cooler air or hotter air?

1. Cooler

2. Same for both

3. Hotter

4. Cannot be determined.

Q.

What is light according to Einstein?

Why does it follow rectilinear propogation? Why does it what to acquire the shortest distance between two points? And what is that that gives energy to the light particles to gain motion??

Q. Calculate the speed of light in a medium which has its refractive index as $\mu =1.5$

Q. what is the refractive index of gold