Refraction Of Light

An optical fibre is a transparent thin fibre, usually made of glass or plastic for transmitting light Optical fibres are used in imaging optics, and work on the principle of total internal reflection of light. Bundles of fibres are used along with lenses for long, thin imaging devices called endoscopes, which are used to view objects through a small hole. Medical endoscopes are used for minimally invasive exploratory or surgical procedures (endoscopy).

To determine how reducing the length of a filament by 10% affects the power of a heater, we need to consider how the resistance of the filament changes and how that impacts the power output.
Step 1: Understanding Resistance and Power Relationship
The resistance ( ) of a filament is given by:

where:
- is the resistivity of the material,
- is the length of the filament,
- is the cross-sectional area.
If the length ( ) is reduced by 10%, the new length is:

Step 2: Effect on Resistance
The new resistance with the reduced length can be written as:

Step 3: Power Relationship
The power ( ) of the heater is related to the voltage ( ) and resistance ( ) by:

With the new resistance , the new power is:

Step 4: Comparing Powers
The ratio of the new power to the original power is:

Conclusion:
If the length of the filament of a heater is reduced by 10%, the power of the heater will increase by approximately 11%.
The correct answer is option (C): Increase by 11%

The correct answer is option (B): 60°