• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Physics: Post your doubts here!

Suchal Riaz

Suchal Riaz

Messages
1,983
Reaction score
3,044
Points
273
if you have casio fx 991ES or other good calculator here is how to do this:
press mode press 4
now write a decimal number, lets say 125 and press =
now press shift+log
it will show the binary as 000000001111101
all you need it 11111101
 
talha-_-khan

talha-_-khan

Messages
71
Reaction score
76
Points
28
Need this answers with a little explanation please
001.jpg

 
Thought blocker

Thought blocker

Messages
8,477
Reaction score
34,837
Points
698
chocolate_girl said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w04_qp_1.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w04_er.pdf

helpp with exp in mcq
2
7
20
31
ty in advance
Suchal Riaz
Click to expand...
2) A and D must not be the answer, Its obvious.
the answer is C. because unit current is not like unit charge.
current is how many electrons in a second i.e. e/second, which has Amps as its unit.
Charge is Coulomb with a unit C. so both of them are NOT the same.
p.d.= work done/unit charge NOT work done/current SO Answer is not B

7) 20) Suchal Riaz ZaqZainab

31) Before we select an answer, let's review what each answer means.

A. The mathematical expression of this statement is F = E*q. Voltage (potential difference) is not a force, and the E here is an electric field not a difference in potential, so this answer cannot be correct.

B. Energy = V*q = d*E*q is the mathematical expression referred to here. Since I (current) = dq/dt, q = I*t (current is the derivative of charge with respect to time, thus total charge is current times total time passed). This means Energy = V*q (voltage times charge) = V*I*t (voltage times average current times time elapsed), which can be rearranged to say V = E/(I*t). This is not the ratio of energy to current, rather the ratio of energy to charge passed, so this answer cannot be correct.

C. Power = V*I. Thus V = P/I. This is a correct assessment of potential difference. Saying that potential difference in a wire is equal to the ratio of power to current is correct, since V = P/I, so this answer is acceptible.

D. P = V*I = V*dq/dt, which means V = P/(dq/dt). You can go one step further and integrate the top and bottom of this equation and say V = int(dE/dt)/int(dq/dt) = E/q. In neither case is the potential difference the ratio of power to charge moved, it is either the ratio of power to charge moved per second (current), or it is the ratio of the energy dissipated to the charge moved. So this answer is unacceptible.

Thus the answer is C.
 
chocolate_girl

chocolate_girl

Messages
140
Reaction score
134
Points
38
Thought blocker said:
2) A and D must not be the answer, Its obvious.
the answer is C. because unit current is not like unit charge.
current is how many electrons in a second i.e. e/second, which has Amps as its unit.
Charge is Coulomb with a unit C. so both of them are NOT the same.
p.d.= work done/unit charge NOT work done/current SO Answer is not B

7) 20) Suchal Riaz ZaqZainab

31) Before we select an answer, let's review what each answer means.

A. The mathematical expression of this statement is F = E*q. Voltage (potential difference) is not a force, and the E here is an electric field not a difference in potential, so this answer cannot be correct.

B. Energy = V*q = d*E*q is the mathematical expression referred to here. Since I (current) = dq/dt, q = I*t (current is the derivative of charge with respect to time, thus total charge is current times total time passed). This means Energy = V*q (voltage times charge) = V*I*t (voltage times average current times time elapsed), which can be rearranged to say V = E/(I*t). This is not the ratio of energy to current, rather the ratio of energy to charge passed, so this answer cannot be correct.

C. Power = V*I. Thus V = P/I. This is a correct assessment of potential difference. Saying that potential difference in a wire is equal to the ratio of power to current is correct, since V = P/I, so this answer is acceptible.

D. P = V*I = V*dq/dt, which means V = P/(dq/dt). You can go one step further and integrate the top and bottom of this equation and say V = int(dE/dt)/int(dq/dt) = E/q. In neither case is the potential difference the ratio of power to charge moved, it is either the ratio of power to charge moved per second (current), or it is the ratio of the energy dissipated to the charge moved. So this answer is unacceptible.

Thus the answer is C.
Click to expand...

thanks and in mcq 2 y is it obvious that A and D r incorrect?
 
You must log in or register to reply here.
Top