a) 2 diff solid with same mass and temp have equal amt of internal energy .
b) object of lower mass has lower internal energy as compared to another object with higher mass
c) object of higher temp have higher internal energy compared to another object with lower temp .
which 1 is true ?
Q2 ) direct current made to flow along insulated wire wound closely on a steel bar , what is the effect of this arrangement ?
ans : will be magnetized with N and S poles.
my answer : will not be magnetized,
problem: am i supposed to assume that mag. field of current can pass thru insulated wire ?
Q3) N,M,O are pith balls which behaves as follows.
M repel N ; M attract O and O repel P .
if P is positively charged,
a)N is negatively charged
b) N is negatively charged or neutral ?
ANS is A . whynot B ?
problem: negatively charged objects canot attract things ?
Q4) which curit dissipates the greatest power ?
A) ciruit connect in series with 2bulbs.
b) curcuit connected in series with 1 bulb
c) curcuit connected in parallel with 1 bulb in each branch .
d) curcuit connected in parallel with 2 branches, ( 1 bulb in 1 branch and 2 bulbs in the other branch)
answer is C
Logic/ thinking process:ans is C OR D as it has the lowest resistance, due to it being parallel . hence higher current, which contribute to greater power ( P=IV )
However, C is the answer instead of D because ... ? ( dunoe how already)
Q5) an illuminated object placed 12cm in front of a thin converging lends. A sharp image appears on a piecce of paper placed alongside the illuminated object wjhen a plane mirror is placed 20cm on the other side of the lens.
Meaning
illuminated object - paper <---- > lens <------------> mirror
<-no distance- > 12 20
mirror is replaced with white screen and illuminated object is placed 24cm away from converging lens.
Q: how far should the white screen be placed from the converging lends such that a clear focused image can be seen on it
( ans is 24)furthermore, it stated that Focal point is 12cm . ( how derive that ?)
Qb : upper half of lens covered with black cloth, stage how image is affected ?
my ans: only half of image formed.
correct ans: image not as bright.
how can ? the light ray canot even pass thru the cloth how form the upper half of image?
Q6 ) copper of mass 10g heated to 10 deg and placed in cavity of huge block of ice at 0 deg. Assuming no heat loss, cal massof ice melted.
heat capacity of copper= 400/j/kg/c
latent heat of fusion = 320000j/kg
Q 7 ) when beam of white light is incident upon glass air interface the rays may
a) suffer no chance of direction
b) refracted away from norm
c) emerge displaced but parallel to org. direction
d) total internally reflected
Which is correct ?
my ans is. a,b, d so whats urs ?
new qn
find power of wheel after 1 revol.
Q1 Key concepts to know:
1) Internal energy is sum of potential energy + kinetic energy of molecules of the system
2) Temperature is the measure of the kinetic energy of the molecules of the system
a) not true because same temperature doesn't mean same internal energy. Different potential energy for different solids
b) not true because temperature not taken into consideration
c) not true because potential energy not taken into consideration.
Q2 Key Concept to know:
1) Magnetic fields cannot pass through magnetic materials only. That's why magnetic materials are used for magnetic shielding, i.e. in expensive speakers.
So yes, can be magnetised. Normal solenoids are also insulated, if not short circuit liao...
Q3 Key Concepts to know
1) Only like poles repel (so only magnets can repel)
2) Unlike poles attract... also, neutral magnetic material and poles attract
M repel N ; M attract O and O repel P .
M, N, O and P can repel, so all are magnets.
P is positive, so O is positive, so M and N are negative.
None are neutral
Q4) which curit dissipates the greatest power ?
A) ciruit connect in series with 2bulbs.
b) curcuit connected in series with 1 bulb
c) curcuit connected in parallel with 1 bulb in each branch .
d) curcuit connected in parallel with 2 branches, ( 1 bulb in 1 branch and 2 bulbs in the other branch)
answer is C
Logic/ thinking process:ans is C OR D as it has the lowest resistance, due to it being parallel . hence higher current, which contribute to greater power ( P=IV )
However, C is the answer instead of D because ... ? ( dunoe how already)
Following your train of thoughts, C is the answer because C has even lower resistance than D ;)
Q5) an illuminated object placed 12cm in front of a thin converging lends. A sharp image appears on a piecce of paper placed alongside the illuminated object wjhen a plane mirror is placed 20cm on the other side of the lens.
Meaning
illuminated object - paper <---- > lens <------------> mirror
<-no distance- > 12 20
mirror is replaced with white screen and illuminated object is placed 24cm away from converging lens.
Q: how far should the white screen be placed from the converging lends such that a clear focused image can be seen on it
( ans is 24)furthermore, it stated that Focal point is 12cm . ( how derive that ?)
Qb : upper half of lens covered with black cloth, stage how image is affected ?
my ans: only half of image formed.
correct ans: image not as bright.
how can ? the light ray canot even pass thru the cloth how form the upper half of image?
Key concepts to know: Parallel rays will converge at the focal point
What happened: light travels from object through lens, reflected at mirror, go past lens again, and produce image at same point.
Only way it is possible, object was at focal point, so go past lens ==> parallel rays, reflect back as parallel rays, then converge at focal point again. So focal length is 12 cm
Then recall your different scenarios. Objects placed at 2 times focal length (2f) will produce an image at 2f. Hence, screen should be put at 24 cm
Part b is a very common question.
Image is less bright because light rays travel in all directions, and will still reach the lens... Any rays from any portion of the object will still be able to reach the lens, and converge to form the image on the screen
For this question..
"
Q4) which curit dissipates the greatest power ?
A) ciruit connect in series with 2bulbs.
b) curcuit connected in series with 1 bulb
c) curcuit connected in parallel with 1 bulb in each branch .
d) curcuit connected in parallel with 2 branches, ( 1 bulb in 1 branch and 2 bulbs in the other branch)
answer is C
Logic/ thinking process:ans is C OR D as it has the lowest resistance, due to it being parallel . hence higher current, which contribute to greater power ( P=IV ) "
The answer is C? YAY !
I took a physics test on Monday and this question came out. At first I thought it was ( D ) but then after calculations etc.. then I got the answer to be C...+1 mark for mcq.
Wah no one else do ah
Q6 ) copper of mass 10g heated to 10 deg and placed in cavity of huge block of ice at 0 deg. Assuming no heat loss, cal mass of ice melted.
heat capacity of copper= 400/j/kg/c
latent heat of fusion = 320000j/kg
Energy required to cool copper to 0 degrees = 0.01 * 400 * 10 = 40 J
Energy required to melt ice = m * 320000 = 40
m = 0.125 mg
Q 7 ) when beam of white light is incident upon glass air interface the rays may
a) suffer no change of direction
b) refracted away from norm
c) emerge displaced but parallel to org. direction
d) total internally reflected
Which is correct ?
my ans is. a,b, d so whats urs ?
you are correct