Physics - Study Mode

[#1246] Ball pen functions on the principle of :
Correct Answer

(D) Surface tension

Explanation

Solution: The ballpoint pen is one of the most simple and yet ubiquitous devices whose function depends on surface tension. With a pen held upright, gravity and surface tension act in concert to get ink onto the ball.

[#1247] When a detergent is added to pure water, its surface tension
Correct Answer

(B) Decreases

Explanation

Solution: When detergent is added to water, it decreases the surface tension of the water. Compounds that lower water's surface tension are called surfactants, which work by separating the water molecules from one another.

[#1248] Pieces of camphor placed on water move about rapidly. This is because of
Correct Answer

(C) Surface tension

Explanation

Solution: The Camphor slowly dissolves in the water lowering the latter's surface tension in the immediate neighbourhood. The stronger pull exerted by the uncontaminated portion of water brings about a movement of the surface and the camphor particles are carried along with it. When after sometime the whole surface settles for the reduced tension, the movement of the camphor too short.

[#1249] What is unit of Viscosity ?
Correct Answer

(B) Newton second per square meter

Explanation

Solution: The SI unit of dynamic viscosity is the newton-second per square meter.

[#1250] The hair of shaving brush clings together when removed from water due to
Correct Answer

(A) Surface tension

Explanation

Solution: When the brush is taken out of water, the hairs cling together due to surface tension. This happens because the free surface of water tries to acquire a minimum surface area.