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

A coil of insulated copper wire is wound around a piece of soft iron and current is passed in the coil from a battery. What name is given to the device so obtained? Give one use of the device mentioned by you.

Show with the aid of a diagram how a wire is wound on a U-shaped piece of soft iron in order to make it an electromagnet. Complete the circuit diagram and label the poles of the electromagnet.

State two ways through which the strength of an electromagnet can be increased. 

Name one device that uses an electromagnet.

State two advantages of an electromagnet over a permanent magnet.

State two differences between an electromagnet and a permanent magnet.

Why is soft iron used as the core of the electromagnet in an electric bell?

How is the working of an electric bell affected, if alternating current be used instead of direct current? 

Name the material used for making the armature of an electric bell. Give a reason for your answer. 

Atmospheric pressure at sea level is 76 cm of mercury. Calculate the vertical height of the air column exerting the above pressure. Assume the density of air 1.29 kgm⁻³ and that of mercury is 13600 kgm⁻³. Why the height calculated by you is far less than the actual height of the atmosphere?

The radius of the press plunger and pump plunger are in ratio of 50 : 4. If an effort of 20 kgf acts on the pump plunger, calculate the maximum effort which the press plunger can over come.

Select the correct option.

As we move upwards, the atmospheric pressure

Select the correct option.

The atmospheric pressure on the earth’s surface is approximately

By drawing a neat diagram define the following:

Mirror

Explain the following term:

Normal Draw

diagram/diagrams to show them.

A ray of light strikes a plane mirror, such that the angle with the mirror is 20°. What is the value of angle of reflection? What is the angle between the incident ray and the reflected ray?

Prove experimentally that images are formed as far behind in a plane mirror as the object is in front of it.

Prove geometrically that when plane mirror turns through a certain angle, the reflected ray turns through twice the angle.

(a) What do you understand by the term lateral inversion?
(b) A printed card has letters PHYSICS. By drawing the diagram show the appearance of the letters. (No ray diagram is required).

State the mirror formula for the formation of total number of images formed in two plane mirrors, held at an angle.