ICSE − Q & A

In Newton's first law of motion.... Is it okay if we write it as.... unless an external "unbalanced" force is applied on it. This statement is right but will they deduct marks for it being not exactly same to the def. given in the text book?

How does resistance depend on the area of cross section of a conductor?

http://www.respaper.com/harshavvardhan/774/6557-zip.html q7 -c with answers reasons please

Is osterd's law there in syllabus?
If yes then please explain in short.

what is the energy change during respiration?pls answer asap

explain "critical angle of diamond is 24"

WORKING OF THE CRT
Loads of people have trouble understanding this so I thought I'd help make it a little simpler :] 

1) Filament heats the Cathode. 
2) Cathode gets charged and emits the electrons
3) Grid(situated between Anode and Cathode) directs the entry of electrons
4) Anode provides Kinetic energy to the electrons
5) Deflecting plates direct the electrons to the flourascent screen. 

This is the process of how an electrical signal is converted into a visual signal. Please correct me if I made any mistake. 
Hope I helped :]

Suresh applies a force of 6kgf to draw a 4.8kg bucket of water from a well using a single fixed pulley. Assuming all extra force is used to overcome frictional forces, calculate MA, VR, eff.
ans should be 0.8 MA, VR is 1 and eff. 80% right?

I have a question that my friend asked me:
Consider two heating devices A and B which use a wire of high resistance to produce heating effect.
Let the Resistance of A be x and that of B be 2x
So B should produce more heat.(as the resistance of wire is double)
But V = IR(so I is inversely proportional to R)
So let the current in A be y, so the current in B should be y/2
According to H = I^2RT
Heat produced is directly proprtional to the SQUARE of I(current)
So the heat produced by B must be less than that by A.
Which heater produces more heat?

what is the exact meaning of power rating ?