Q&A - Ask Doubts and Get Answers

Sort by :

How many stars in milky way?

Most of the space research agencies estimated the count as 100 billion. The maximum estimated number of stars in the milky way is  400 billion. The estimate given by The European Space Agency says there are around 100 billion stars in the milky way. Generally, we can say about 100 to 400 billion stars are said to be there in the milky way (1 billion = 100 crore=10,000 lakh)

1 2 3 4 5 6 7 ?

acc. to series the ans. is 8

3.20 b) Given the resistances of 1 Ω, 2 Ω, 3 Ω, how will be combine them to get an equivalent resistance of (iii) 6 Ω

Attach them in series

Question 6. Let ∗ be the binary operation on N given by a ∗ b = L.C.M. of a and b. Find

(v) Which elements of N are invertible for the operation ∗?


Who noticed the deflection of the compass needle every time the current was passed through the wire? When an electric current flows through a wire, it behaves like a magnet.

Hans Christian Oersted was the first person who noticed the deflection of the compass needle every time the current was passed through the wire. When an electric current flows through a wire, it behaves like a magnet.
It can be done by Connecting a large Resistance R in series with the Galvanometer

what is the difference between the two ?

The prefix poly means many. So the word polynomial refers to one or more than one term in an expression. The relationship between these terms may be sums or differences. You call expression with a single term a monomial, an expression with two terms is a binomial, and expression with three terms is a trinomial. Here we are only discussing Binomial along with their exponents.

pressure inside a liquid jet in excess of atmostpheric pressure . for example if aglass tube of samll diameter is partially immersed in water , the water will wet the surface of the tube ant it will rise in the tube to some height above the normal water surface . In this case, the water surface is concave upward.


  • In this collision (K.E)_{initial} \neq (K.E.)_{final}

  • Coefficient of restitution 0 < e < 1 

  • As (K.E)_{initial} > (K.E.)_{final}

The loss in kinetic energy appears in other forms, such as heat, sound etc. 

Ex- Collision between two billiard balls. All majority of collision belong to this category.

in inelastic collision k. e. is conserved

Intrinsic semiconductors are a pure form of semiconductors. Extrinsic semiconductors are obtained when an impurity is added to an intrinsic semiconductor.

Intrinsic semiconductors are the ones which are semiconductors by nature. For example silicon and Germanium (group 14 elemets). But these elements are conductors  of electricity  at high temperatures and at room temperature they are insulators. Even when we provide high temperature they are poorly conducting ie they conduct but it is not enough. so In order to improve their conductivity we Dope...
If not then the loss in kinetic energy is transferred into which form of energy??



Which of the species is more stable O or N? Nitrogen is more stable than Oxygen due to half-filled electrons in Nitrogen.

Both are active, but O is more active w.r.t. N due to its high electronegativity[ En(O) = 3.5 & En(N) = 3.0 ]. Hence, N is more stable w.r.t. O

A massless rope is fixed at one end as shown in fig. Two boys of masses 40kg and 60kg are moving along the rope. The former climbing up with an accelaration of 2m/s^2 while  later coming down with constant velocity of 5m/s. The tension at fixed support will be (g=10m/s^2)

Nucleophilicity is highest in polar aprotic solvents, and lower in polar protic solvents because polar protic solvents (like water) can make H-bond and it will ultimately make the nucleophile more bulky. E.g. of polar protic solvents - H2O, CH3OH, CH3CH2OH, CH3COOH, H2SO4 E.g. of polar protic solvents - DMSO, Acetone, DMF, HMPA, Acetonitrile  If the solvent is polar aprotic, it’s safe to assume...

CTSE results will be out very soon !!!

Physics has many definitions. In simple words Physics is branch of science concerned with the nature and properties of matter and energy

phsiyics is consist of all kind of physical property   

You just finished Kinematics

In this chapter, you have completed: 19 concepts 17 doubts More than 30 Questions and Examples In this chapter, firstly you read Concepts of “Kinematics” and then moved to “applications of kinematics”. Apart from this, there are certain tips for you which will be helpful for you to develop a lot of interest in this chapter. There are some examples as well as practise question in each...
CTSE results will be out very soon.
Here is the solution:

Time (T), velocity (C) and angular momentum (h) are chosen as fundamental quantities instead of mass, length and time. In terms of these, the dimensions of mass would be :

Dimension of length