Physics Tutors in Delhi University, Delhi

The main good sides of the Friction are : i) It helps us in walking on ithe ground properly without slipping, ii) It helps us keep our palms warm during winter on rubbing, iii) It enables the car come to rest slowly by applying brakes.

Barkhausen criterion is applicable to oscillators. It provides a set of conditions for sustained oscillations.Oscillators work on the principle of positive feedback or regenerative feedback. That is, a fraction of output (from amplifier) is taken and added back to input with proper MaGnitude and phase. By doing so, output regenerates eventhough input is removed. However, to Make it happen, Barkhausen criterion has to be satisfied which states:

(1) Magnitude of overall gain around the loop should be unity.

Energy gap:

In solid-state physics, an energy gap is an energy range in a solid where no electron states exist, i.e. an energy range where the density of states vanishes. Especially in condensed-matter physics, an energy gap is often known More abstractly as a spectral gap, a term which need not be specific to electrons or solids.

Germanium which makes Ge more conductive as compared to Si. The energy gap for germanium is less (0.72eV ) than the energy gap of silicon (1.1eV). But the present trend is to use Silicon instead of Germanium in many devices like SMPS etc.

The easiest experiment to prove that light travels in a straight line needs only three post cards Make small holes with a pin at the centre of each card. Then light a candle in a dark room, place it on a table safely. Take the help of three helpers (like your brothet/sister/friend/any other person). Draw a straight line on the floor with a scale or a plastic water pipe. Now when the three of your helpers stand on the striaght line with their cards placed at the same height, the last persom away from the candle can see the candle. If there is slightest difference in the level or alignment in the centre of the cards that they are holding, then the candle will not be visible to the last person away from the candle. 

Answer: 0.375 Amp  Option 1

Pl refer to the attachment for detailed explanation 

hat is a force?

Newton’s First Law of motion defines force.

It says that every body continues to be in its state of rest or in its state of uniform motion in a straight line till such time as an external FORCE starts acting on it.  The force

•Causes its velocity to change-either the body moves faster or it slows down, or

•Causes its direction of motion to change, or

•Causes its shape to change-like when we apply force on a dough of flour (atta), its shape changes

Newton’s Second Law of motion helps us to measure this force.

It says that the rate of change of momentum is proportional to the external force.

We know momentum is mass x velocity.

So Force = P= rate of change of momentum = mass x rate of change of velocity = mf

Since rate of change of velocity is also called acceleration

Newton’s Third Law of motion

It simply says that every action has an equal and opposite reaction.

When you are standing, you apply a force equal to your mass x acceleration due to gravity on the floor, the floor also exerts an equal and opposite force on you.

By the formula, a = v^2/r , the angular acceleration of the object = (4^2)/0.25 = 64 m/(s^2) .   (Ans.)  

S=ut+1/2at^2 10 =1/2*a*4 a=5 F=2*5=10N

P=I V dW/dt =ILdI/dt dW=LdI Integrating both sides W=1/2LI*I