Question

1. Two slits are 0.08mm apart, and the screen is 1.5m away. How far is the 3rd dark fringe located from the central maximum if light of wavelength 600 nm is used?
   1. 3.75 cm
   2. 2.81 cm
   3. 3.75 m
   4. 2.81 m

2. Light (600nm) strikes a grating ruled with 350 lines/mm. What is the angular deviation of the 2nd order bright fringe?

1. 21.1 degree
2. 22 degree
3. 24.8 degree
4. 25.4 degree

3. What is light?

1. What we see with our eyes
2. a form of energy that travels in waves
3. A form of work that reflects

4. What tool can be used to differentiate white color light into different colors?

1. Mirror
2. Camera
3. Prism
4. hammer

5. Reflection happens when light strikes and then ___________a surface

1. breaks
2. bounces off
3. reflects

6. A meter stick moves at 0.6c relative to an observer. What is the relative length as seen by the observer?

1. 43.6 cm
2. 0.436 m
3. 80 m
4. 0.80 m

7. According to the theory of relativity, the speed of light in a vacuum is ________for all observers.

1. Different
2. Dependant on the motion of the source of light
3. The same
4. Dependant on the relative motion of the observer
5. All the above

8. You are riding in a spaceship that has no windows, radios, or other means for you to observe or measure what is outside. You wish to determine if the ship is stopped or moving at constant velocity. What should you do?

1. You can determine if the ship is moving by determining the apparent velocity of light.
2. You can determine if the ship is moving by checking your precision timepiece. If it's running slow, the ship is moving.
3. You can determine if the ship is moving either by determining the apparent velocity of light or by checking your precision timepiece. If it's running slow, the ship is moving.
4. You should give up because you have taken on an impossible task.

9. If you were to measure your pulse rate while in a spaceship moving away from the Sun at a speed close to the speed of light, you would find that it was

1. Much faster than normal
2. Much slower than normal
3. The same as it was here on Earth

10. As the speed of a particle approaches the speed of light, the mass of the particle

1. Increases.
2. Decreases.
3. Remains the same.
4. Approaches zero.

Answer 1

(1) Seperation between slits = d = 0.08 mm, distance of the screen from the slits = D = 1.5 m = 1500 mm,

wavelength of the light used = = 600 nm = 0.0006 mm.

Hence, fringe width = y = D / d = ( 1500 x 0.0006 / 0.08 ) mm = 11.25 mm.

Hence, third dark fringe, which is in the middle of the second and the fourth bright fringes, will be y / 2 distance away from the second bright fringe.

Therefore, distance of the third dark fringe from the central maxima is :

2y + y / 2 = 2.5y = 2.5 x 11.25 mm = 28.1 mm = 2.81 cm.

Hence, correct option is : (2) 2.81 cm.

(3) Light is a (2) a form of energy that travels in waves.

(4) While travelling through a prism, white light is divided into its constituent colours, and this phenomenon is known as dispersion of light.

Hence, correct option is : (3) Prism.

(5) Reflection happens when light strikes and then (2) bounces off a surface

(7) According to the theory of relativity, the speed of light in a vacuum is (3) the same for all observers.

(10) According to the special theory of relativity, as the speed of a particle approaches the speed of light, the mass of the particle (1) Increases.