Optical Instruments

Step 1: Concept
Magnifying power and length for normal adjustment.
Step 2: Analysis
. .
Step 3: Conclusion
cm and cm.
Final Answer: (A)

Step 1: Graham's Law
Rate of diffusion .
Step 2: Diffusion Order
Masses: . Order of diffusion: .
Step 3: Remaining Gas
The gas that diffuses fastest will have the lowest remaining amount and partial pressure. Order of remaining amount/pressure: .
Final Answer: (b)

Step 1: Understanding the effect of an object on the telescope's image.
A telescope works by using two lenses: the objective lens (which gathers light) and the eyepiece lens (which magnifies the image). The object, when it sits on the objective lens, interferes with the light path and the image formed.

Step 2: Effect of the housefly on the image.
- The housefly is an opaque object that will block some of the light entering the objective lens. This will result in a reduction in the intensity of the image formed because less light will reach the eyepiece.
- Additionally, the housefly will cause some distortion and may reduce the clarity of the image as well.

Step 3: Conclusion.
The correct answer is (3), as the intensity of the image will be decreased due to the obstruction caused by the housefly.

Step 1: Understanding the Concept:
For a satellite in circular orbit, gravitational force provides centripetal force.
Step 2: Detailed Explanation:
.
KE = .
Step 3: Final Answer:
Thus, KE .

Concept: Resolving power of human eye

Step 1: Use small angle formula

Step 2: Substitute values

Concept: Power of lens:

Step 1: Using lens formula.
With glasses:

Step 2: Without glasses.
Near point of eye = Thus required position: Closest matching option (as per given key):

Concept: Magnifying power of telescope:

Step 1: New focal length.


Step 2: New magnification.