TEST SERIES - 64 (II)

If the top half of a convex lens is covered with black paper

• The bottom half of the image will disappear

• The top half of the image will disappear

• The magnification will reduced to half

• The intensity will be reduced to half

In a cinema hall, the distance between the projector and the screen is increased by 2%. Then, the intensity of illumination of the screen is

• Decreased by 2%

• Decreased by 4%

• Increased by 2%

• Increased by 4%

When a CD (compact disc used in audio and video systems) is seen in sunlight. Rainbow like colours are seen. This can be explained on the basis of the phenomenon of

• Reflection and diffraction

• Reflection and transmission

• Diffraction and transmission

• Refraction, diffraction and transmission

An explosion takes place on the surface of moon. An astronaut at some distance from the site of explosion will

• Observe light and hear sound caused by the explosion

• Observe light but not hear sound caused by the explosion

• Hear sound but not observe light caused by the explosion

• Neither hear sound nor observe light caused by the explosion

What is viewed through an electron microscope?

• Electrons and other elementary particles

• Structure of bacteria and viruses

• Inside of human stomach

• Inside of the human eye

To observe diffraction, the size of the obstacles

• Should be of the same order as the wavelength

• Should be much larger than the wavelength

• Has no relation to wavelength

• Should be exactly half the wavelength

Plane mirrors and are kept at angle with respect to each other. Light falls on is reflected then falls on and is reflected. The emergent ray is opposite to the incident direction. The angle is equal to

• 30°

• 45°

• 60°

• 90°

Why is red light employed for danger signals?

• Red colour is soothing to the eye

• Human eye is most sensitive to red colour

• Red light is scattered least

• Red light is scattered most

Whose experiments proved that the speed of light was always the same?

• James Clark Maxwell

• Michelson and Marley

• Miller and Stanley

• Werner Heisenberg

Consider the following statements: 1. The focal length of the objective of a microscope is less than the focal length of the eyepiece. 2. The minimum distance between an object and its real image formed by a convex lens of focal length f is equal to 4f. Which of the statements given above is/are correct?

• Only 1

• Only 2

• Both 1 and 2

• Neither 1 nor 2