Physics Online Quiz

A parabolic concave mirror is used in torches and car headlamps as reflectors. This type of mirror is capable of directing the light at a particular point as they have converging power. These mirrors provide clear visibility.

Ammeter is an instrument for measuring either direct or alternating electric current, in amperes.

Water and petrol are immiscible with each other and petrol which forms the upper layer continues to burn. Water is heavier than petrol, petrol will come above the water and continue the contact with the atmosphere (oxygen).

Smells travel through the air by a process called diffusion; air particles, and the odour particles within the air, move freely in all directions. They are constantly moving and eventually they spread out through the air around them.

Danger signs are red because air, water, and dust molecules scatter red light the least. Scattering has an inverse relationship with the fourth power of the wavelength of a particular colour. Because red has the longest wavelength of all the colours, it is the least dispersed.

The density of air becomes heavier near the surface of the earth (due to gravity) and begins to lighten as we go to higher altitudes as the air becomes rarer. Thus, atmospheric pressure decreases with increase in altitude.

When a bus suddenly takes a turn the passengers are thrown outwards due to the property of inertia. As the passengers are still in their straight motion so they fall outwards.

A concave lens is used to minimize the proportions of the objects and gives a wider view of the object or area. It always forms virtual, erect and diminished image.

X-ray inspection systems are mostly capable of detecting defects and contaminants in precious stones and diamonds.

The Plimsoll line is a reference mark located on a ship's hull that indicates the maximum depth to which the vessel may be safely immersed when loaded with cargo.