To naked eye, ----- is just a gleaming bright spot.

Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes under a microscope, which sample would you carry and why?

Naked seeds occur in

A convex lens of diameter 8.0 cm is used to focus a parallel beam of light of wavelength 620 nm. If the light be focused at a distance of 20 cm from the lens, what would be the radius of the central bright spot formed ?

One can sense colours only in bright light.

The one parameter that determines that brightness of a light source sensed by an eye is

Answer the following questions: (c) When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the shadow of the obstacle. Explain why?

Light of wavelength 560 nm goes through a pinhole of diameter 0.20 mm and falls on a wall at a distance of 2.00 m. What will be the radius of the central bright spot formed on the wall ?

A balloon of radius r subtends an angle alpha at the eyes of an observer and the center of balloon from the eye is beta . Find the height of the center of the balloon from the eye of observer .

What is Angular leaf spot?