Question
The danger signal lights are red in colours.
✓
Answer
The red light gets scattered least by fog or smoke because of its longer wavelength relative to light of any other colour. So, it can be seen even from a long distance. Therefore it is used in signals showing danger.
Colloidal solution and colloidal particles : The solution in which the particles of material do not mix or dissolve in the solvent is called colloidal solution and these particles of colloidal solution are known as colloidal particles.
Examples of colloidal solution or material : Sodium thiosulphate $\left( Na _2 S_2 O _3\right)$, milk, butter, smoke, soap-lather.
Colloidal solution and colloidal particles : The solution in which the particles of material do not mix or dissolve in the solvent is called colloidal solution and these particles of colloidal solution are known as colloidal particles.
Examples of colloidal solution or material : Sodium thiosulphate $\left( Na _2 S_2 O _3\right)$, milk, butter, smoke, soap-lather.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Explain how is hand pulled away from the hot object reflexly.
Give the deference : Series combination of resistors and Parallel combination of resistors.
Write the preparation of baking soda with reaction and uses.
State reason for the following statements:
$(i)$ Tap water conducts electricity whereas distilled water does not.
$(ii)$ Dry hydrogen chloride gas does not turn blue litmus red whereas dilute hydrochloric acid does.
$(iii)$ During summer season, a milk man usually adds a very small amount of baking soda to fresh milk.
$(iv)$ For a dilution of acid, acid is added into water and not water into acid.
→$(i)$ Tap water conducts electricity whereas distilled water does not.
$(ii)$ Dry hydrogen chloride gas does not turn blue litmus red whereas dilute hydrochloric acid does.
$(iii)$ During summer season, a milk man usually adds a very small amount of baking soda to fresh milk.
$(iv)$ For a dilution of acid, acid is added into water and not water into acid.
Two coils of insulated copper wire are wound over a non-conducting cylinder as shown in figure $13.28$. Coil $1$ has larger number of turns.
$(1)$ Write your observations when, $A$. plug key $K$ is closed and $B$. plug key $K$ is opened. $(2)$ Give reason for your observations. $(3)$ Mention the name of the phenomenon involved and define it. $(4)$ Write the names of two coils used in this experiment. OR What are these coils called?
→$(1)$ Write your observations when, $A$. plug key $K$ is closed and $B$. plug key $K$ is opened. $(2)$ Give reason for your observations. $(3)$ Mention the name of the phenomenon involved and define it. $(4)$ Write the names of two coils used in this experiment. OR What are these coils called?
Explain the excretory system of human being.###Explain the excretory organs in human being.
In which condition is the magnetic force acting on a given current-carrying rod placed in a magnetic field maximum and in which condition would the magnetic force not act on the rod?
(Assume that the current through the rod and the strength of the magnetic field are not changed.)
(Assume that the current through the rod and the strength of the magnetic field are not changed.)
Explain: Strong acid and weak base .
Which products are obtained when metals react with water? Explain the reaction of metals such as potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), aluminium (Al), iron (Fe), zinc (Zn), lead (Pb), copper (Cu), silver (Ag) and gold (Au) with water.
Explain with appropriate diagram Newton's experiment showing that white light of the Sun (sunlight) is composed of seven colours.###How did Newton show that white light of the Sun (sunlight) contains seven colours using two identical glass prisms?###Describe the activity to show that the colours of white light splitted by a glass prism can be recombined to get white light by another identical glass prism. Also draw ray diagram to show the recombination of the spectrum of white light.