Refraction Of Light

Magnification of a Concave Mirror

An object is placed 10 cm in front of a concave mirror. The image is at 20 cm from the mirror on the same side of the object. We need to find the magnification produced by the mirror.

Step 1: Sign Conventions

* Object distance (u): Distance of the object from the mirror. Always taken as negative when the object is in front of the mirror. * Image distance (v): Distance of the image from the mirror. Negative if the image is on the same side as the object (virtual image), positive if on the opposite side (real image).

Step 2: Given Values

* Object distance: * Image distance: (since the image is on the same side as the object)

Step 3: Magnification Formula

The magnification (m) is given by:

Step 4: Calculate Magnification

Plugging in the values:

Conclusion

The magnification produced by the mirror is -2.

We are given:

• Apparent depth in water = 9 cm
• Refractive index of water,
• Refractive index of new liquid,

Step 1: Find the real depth using the water's refractive index:

Step 2: Use the real depth to find the new apparent depth:

Final Answer:

When light travels from a rarer medium to a denser medium, its speed decreases. Since the frequency of light remains constant when it enters a new medium, its wavelength decreases.
The relationship between the speed , frequency , and wavelength is given by:
Since the frequency remains constant and the speed decreases in a denser medium, the wavelength must decrease.
Hence, the correct answer is (D).