(English Medium) ICSE Class 9 - CISCE Question Bank Solutions

State whether the following statement is true or false. If false, correct it.

If a ray of light incident on a plane mirror is such that it makes an angle of 30^o with the mirror, then the angle of reflection is 60^o.

State whether the following statement is true or false. If false, correct it.

If the incident ray makes an angle of X^o with the normal, then the reflected ray is 2X^o.

State whether the following statement is true or false. If false, correct it.

The image formed in a plane mirror is the real, erect, and same size as that of the object.

State whether the following statement is true or false. If false, correct it.

The image in a plane mirror is situated in the mirror.

Explain how the principle of echo is used by
The bat during its flight at night

Explain how the principle of echo is used by
The dolphin to locate small fish as its prey.

A person hearing at one end of a long metal bar hears two distinct sounds when the other end is struck with a stone. Explain, giving scientific reasons

What do you mean by the frequency of sound?

What is the SI unit of frequency?

Define one hertz.

What type of sound is produced by elephants and whales?

What do you mean by an echo?

What is echolocation? How do animals make use of this phenomenon?

Name the Sound of the Frequency Given Below:
200 Hz

When a ray of light strikes a plane mirror at an angle of 150 with the mirror, what will be the angle through which the ray will deviate? Illustrate with a ray diagram in the following figure.

The word PLATE written on a paper is held in front of a plane mirror. Write down the letters as seen in the following case.
The paper is held parallel to the mirror.

The word PLATE written on a paper is held in front of a plane mirror. Write down the letters as seen in the following case.
The paper is held perpendicular to the mirror.