Physics Questions

The size of the pupil of the eye automatically adjusts itself  according to the intensity of light passing through it;if the intensity is more , the size is less, if less, it is more. So in our case the pupil should dilate i.e, increase in size to be able to see in the dark . This switchover takes sometime. But here the entry into the dark room is immediate . So the eye has no time to adjust itself and hence is not able to see at all for a while.

The submerged portion of the ice on melting shrinks a little in volume. so the level of water goes down a little.But this is just made up by the water added by the melting of upper portion. Addition is equal to the Shrinkage. Hence level is unchanged.

An object at rest may have Potential energy.

We know that,

The equivalent K =  L1 + L2L1K1+L2K2

where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.

But here L1 = L2 = L (say)

Then K = L+L/(L/K1 + L/K2)  =  2K1K2K1+K2

Time does not depend on mass, else

T ∞ 1 + k2R2 

  k2R2=> is least for 'sphere' and

hence least time is taken by sphere.

The hertz (Hz) is defined as one cycle per second and is a SI unit of frequency. Here kilohertz is also a unit of frequency of waves and is defined as 1000 cycles per second. Radio waves are measured in kilohertz (KHz).

When their is a colloid in the solution, then it will show the Brownian movement, such as dust particle in the air will show the Brownian movement.

Hence, Brownian movement arises due to the impact of the molecules of the dispersion medium with the colloidal particles. It has been postulated that the impact of the molecules of dispersion medium on the colloidal particles are unequal.

This leads to the zig-zag (random) motion of the colloidal particles.