Physics, Chemistry and Biology: Post your doubts here!

[Iridescent]

Im sorrrryyy but I have one more doubt :$,

Same paper, question 34

The answer is C. The magnetic field around a wire carrying current are concentric circles, and the direction of the magnetic field is anti-clockwise. If we draw a circle thogh A,B,C,D, we find that only C points in the anti-clockwise direction of the magnetic field.

 

[Marwa']

Thankkyouu so muchh !

 

[Iridescent]

Using the right hand grip rule, the current is out of the page so your thumb should be pointing out of the page and the rest of our fingers will show the direction of magnetic field, it is C because the compass is pointing in the right direction.

Right hand grip rule? Don't we use Maxwell's screw rule for this? Right hand grip rule is for a ferrous metal inside a solenoid and we use the rule to find the North and the South pole of the magnet formed. Correct me if i'm wrong.

 

[omaaaar]

So is it the position of the thumb which determines the compass

 

[CVB15]

Guys, pls do me a favor and post some notes on thermal capacity asap!!

 

[Marwa']

I have no idea what is Maxwell's screw rule, but i know that the right hand grip rule applies for this and for metals in a solenoid

 

[Othman]

Right hand grip rule? Don't we use Maxwell's screw rule for this? Right hand grip rule is for a ferrous metal inside a solenoid and we use the rule to find the North and the South pole of the magnet formed. Correct me if i'm wrong.

both work for knowing the magnetic field for a wire, but only the right handrule works for the coil.

 

[Othman]

So is it the position of the thumb which determines the compass

No, the thumb is for the direction of current.

 

[Iridescent]

both work for knowing the magnetic field for a wire, but only the right handrule works for the coil.

Okay, I got how Right Hand Grip Rule works for this, I always used the Maxwell's Screw Rule so got a bit confused. Thanx anyway.

 

[Othman]

Guys, pls do me a favor and post some notes on thermal capacity asap!!

An extract from the core syllabus, you can study it from your book;
" Relate a rise in the temperature of a body to an increase in their internal energy, show ad understanding of the term thermal capacity. "

 

[Othman]

Okay, I got how Right Hand Grip Rule works for this, I always used the Maxwell's Screw Rule so got a bit confused. Thanx anyway.

No problem, but it's easier to know one.

 

[Iridescent]

No problem, but it's easier to know one.

Yeah..

 

[omaaaar]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_qp_1.pdf
Q7 answer is A ,but I think it should be C
Q19 donot know how to do
Q23 the ray after passing the lens should converge on the focal point,so how answer can be A
Q30 as both lamps have same voltage so current should be equally divided in the branches,so how answer is B
Q34 I know about the high voltage but the reason I donot know​

 

[Othman]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_qp_1.pdf​

Q7 answer is A ,but I think it should be C​

Q19 donot know how to do​

Q23 the ray after passing the lens should converge on the focal point,so how answer can be A​

Q30 as both lamps have same voltage so current should be equally divided in the branches,so how answer is B​

Q34 I know about the high voltage but the reason I donot know​

Q7) Mass is the same, but volume is different. Density= Mass/Volume. Let's assume a mass I'll take 100g.
100/200 and 100/100. So the Density of X is half the density is Y.

q19) B, convection in air. Hot air is less dense so it moves upwards pushing cold air down. So the air moves in is cool and towards the heater.
q23) When the ray passes through the focus point it must be parallel to the principal axis on the other side of the lens so it is A.

q30 ) P=IV, in parallel the current divides so the power becomes less. Thus the bulbs glow with half brightness, which is D.

q34) B, it talks about transformers when high voltage the current is low so resistance doesn't waste the energy.

 

[omaaaar]

Q7) Mass is the same, but volume is different. Density= Mass/Volume. Let's assume a mass I'll take 100g.
100/200 and 100/100. So the Density of X is half the density is Y.

q19) B, convection in air. Hot air is less dense so it moves upwards pushing cold air down. So the air moves in is cool and towards the heater.
q23) When the ray passes through the focus point it must be parallel to the principal axis on the other side of the lens so it is A.

q30 ) P=IV, in parallel the current divides so the power becomes less. Thus the bulbs glow with half brightness, which is D.

q34) B, it talks about transformers when high voltage the current is low so resistance doesn't waste the energy.

In Q19 why is the direction towards the heater
Q30 the answer in the ms is C why

 

[Othman]

In Q19 why is the direction towards the heater
Q30 the answer in the ms is C why

I forgot that the voltage increases also so that it makes the power the same, so the brightness is full. Sorry for the wrong one.

 

[Othman]

In Q19 why is the direction towards the heater
Q30 the answer in the ms is C why

It is because the hot air from the heater moves upwards moving the cold air down so it must be towards the heater not away because hot air goes away and it is directed to the top.

 

[omaaaar]

I forgot that the voltage increases also so that it makes the power the same, so the brightness is full. Sorry for the wrong one.

In parralel the voltage is maximum is that is why the lamps operate at full brightness

 

[Othman]

In parralel the voltage is maximum is that is why the lamps operate at full brightness

Yeah I forgot that.

 

[omaaaar]

I will be posting more doubts in 10 minutes .will you be there