ALL PHYSICS DOUBTS - POST HERE !!

[~HyDrOgEn~]

thanks another quetion , what is meant by the term efficency!

[Amr Fouad]

thanks another quetion , what is meant by the term efficency!

efficiency is the percentage of useful energy ouytpu.It equals:

(usefyl energy output/total energy input) x 100%

got that?

[~HyDrOgEn~]

Yeah thanks!

[holtadit]

Bimetallic strips ... how do i know which way it bends ?

Consider the scenario where a layer of invar is above copper (expands more than invar).

How and why would it bend ? Any hard and fast rule to rembr this stuff ?

[Saladin]

It would bend upwards.

This is because consider a circle, the outer layer will be longer than the inner layer. Similarly, because coppe expands more, it will be the outer later, and thus the bimetallic strip will bend upwards.

hope dat helps.

[holtadit]

Suggest a suitable full-scale deflection for the ammeter. Give reasons.

What do they mean ? Before this part I had calculated a reading of 0.003 A on an ammeter in a circuit.

[nid404]

Upload the paper please

[holtadit]

Upload the paper please

hang on I have to scan it

[holtadit]

Here

[nid404]

Full scale deflection is the max value displayed on the ammeter...I'd suggest a full scale deflection of 0.01 A...since you measure current with power 10^-3
The full scale value should be the minimum whole value which can offer good linearity and accuracy

[holtadit]

Full scale deflection is the max value displayed on the ammeter...I'd suggest a full scale deflection of 0.01 A...since you measure current with power 10^-3
The full scale value should be the minimum whole value which can offer good linearity and accuracy

I see, I get what you mean.

Heres another:

The pic. shows identical lamps X adn Y in series. The lamps are at normal brightness. A third lamp Z is connected in parallel to X.

What happens to the brightness of lamp y ?

[Amr Fouad]

I see, I get what you mean.

Heres another:

The pic. shows identical lamps X adn Y in series. The lamps are at normal brightness. A third lamp Z is connected in parallel to X.

What happens to the brightness of lamp y ?

falls

[nid404]

Decrease..

Since current through the lamps X n Y decrease...current splits in a parallel circuit

[holtadit]

falls

Even I said that !!!!!

My answer booklet (not the real Markscheme) says it will become BRIGHTER THAN NORMAL..... -_-


Stupid answer booklet...

[Amr Fouad]

The brightness of lamp Y decreases...

Now, X and Z are connected in parallel, and BOTH are in series with Y..