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  • 1 answers

Rishabh Rathi 6 years, 3 months ago

You should consider vectors whose resultant you are finding and the resultant as sides of triangle. When you will draw them like that you will see its obvious that the vertical component comes with sin(sin=P/H) and horizontal component comes with cos(cos=B/H)
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Ankit Patel Chaudhary 6 years, 3 months ago

Thanks to all

Ishani Gupta 6 years, 3 months ago

Energy stored in a capacitor means that the amount of charge required to increase the potential of a capacitor by unit amount . That charge is stored in the form of energy of a capacitor.

Misbahul Haque 6 years, 3 months ago

Energy stored in conducter means increase in potential when it be charging ...
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Sia ? 6 years, 3 months ago

The magnetic force acting on a particle of charge q moving with velocity v in a magnetic field B is given by,

F = qvB
{tex} \Rightarrow {/tex} B = {tex}\frac{F}{qv}{/tex}

Let, F = 1N, q = 1C and v = 1 ms-1
{tex} \Rightarrow {/tex} 1T = 1N / (1C)(1 ms-1) = Ns / Cm

Thus, One Tesla is defined as the strength of magnetic field at the point when a charge of 1 Coulomb moving perpendicularly to the direction of magnetic field at a velocity of 1 ms-1 experiences a force of 1 Newton. 

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Drift velocity is the velocity with which electrons are drifted from one terminal to another terminal on applying potential difference. derivation is not possible here. ?
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▪▪Amrit▪▪ ❤ 6 years, 3 months ago

so that battery of phone get charged
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Navjot Kaur 6 years, 3 months ago

Because the value of temperature coefficient of consfatin & meganin is low. so ,resistance & resistivity don't vary with continuous flow of current.
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Yogita Ingle 6 years, 3 months ago

First law: -

  • According to the first law an emf is induced in the circuit whenever the amount of magnetic flux linked with a circuit changes.
  • Current was induced because of magnetic flux, as there is some current in the circuit therefore there will be some emf flowing in the circuit.
  • Whenever the amount of magnetic flux linked with the circuit changes only at that time emf is induced.

Second law: -

  • According to the second law the magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit.
  • Emf which is induced will depend upon rate at which the magnetic flux is changing.

 

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Sia ? 6 years, 3 months ago


No, the drift speed of electrons is superposed over the random velocities of the electrons and they move in zig- zag path.

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Akriti Trivedi 6 years, 3 months ago

In correct words current is a tenser quantity but commonly we used it as a scalar quantity because it have both magnitude and direction but it doesn't follow vector law so we can't say it a vector quantity

Aman Kumar 6 years, 3 months ago

Wao... That's nice... U both have the correct answer
for more open SL Arora. chapter 3 page no. 3.2 left hand side question no. 5 Is current a scalar or vector quantity. Pura padho. ?
I mean scaler. ? ?
g but usey vector le ker he mana hai chapter mein.

S.....Sharma☺??? .. 6 years, 3 months ago

Ji nahi current na hi scalar h na hi vector it is an tensar quantity tensar means that it does not follow vector as current have direction
current is a scalar quantity becoz it doesn't follow vector law of addition.
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Aman Kumar 6 years, 3 months ago

Becz magnetic field ang current have relation..
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Sia ? 6 years, 3 months ago

Let us consider a circular loop of radius "a" with centre C. Let the plane of the coil be perpendicular to the plane of the paper and "I" be the current flowing in the direction as shown in the figure (coming out from plane of paper normally at top). Suppose P is any point on the axis at a distance "r" from the centre C.

Now, consider a current element "Idl" on top (L) where the current comes out of paper perpendicularly whereas at bottom (M) the current enters into the plane of paper perpendicularly.
{tex}\because \quad L P \perp I d l{/tex}
Also, {tex}M P \perp I d l{/tex}
{tex}\because \quad L P = M P = \sqrt { r ^ { 2 } + a ^ { 2 } }{/tex}

According to Biot-Savart's law,
The magnetic field at point P due to current element Idl
{tex}d B = \frac { \mu _ { 0 } } { 4 \pi } \cdot \frac { I d l \sin 90 ^ { \circ } } { \left( r ^ { 2 } + a ^ { 2 } \right) }{/tex}
where, a = radius of circular loop,
r = distance of point P from centre and along the axis.
The direction of dB is perpendicular to LP and along PQ, so {tex}P Q \perp L P{/tex}.
Similarly, the value of magnetic field at point P due to current element Idl at the bottom is same and its direction is along PQ', where {tex}P Q ^ { \prime } \perp M P{/tex} .
Let ϕ = the angle between LP and CP.
Now, resolving magnetic field dB into two components, (i) dBsinϕ along the axis and (ii) dBcosϕ normally to the axis.
the components dBcosϕ balance each other and axial components are in same direction so get added. So,
Net magnetic field is given by
{tex}B = \oint d B \sin \phi = \oint \frac { \mu _ { 0 } } { 4 \pi } \left( \frac { I d l } { r ^ { 2 } + a ^ { 2 } } \right) \cdot \frac { a } { \sqrt { r ^ { 2 } + a ^ { 2 } } }{/tex} {tex}\left[ {\because In \Delta PCL,\sin \phi = \frac{a}{{\sqrt {{r^2} + {a^2}} }}} \right]{/tex}
or {tex}B = \frac { \mu _ { 0 } I a ^ { 2 } } { 2 \left( r ^ { 2 } + a ^ { 2 } \right) ^ { 3 / 2 } }{/tex}
For N turns, {tex}B = \frac { \mu _ { 0 } N I a ^ { 2 } } { 2 \left( r ^ { 2 } + a ^ { 2 } \right) ^ { 3 / 2 } }{/tex}Tesla.
Magnetic field lines due to a current carrying loop are given by

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Sia ? 6 years, 3 months ago


The donor energy level ED is just below the bottom of the conduction band. It contains the electrons due to added impurity atoms. At room temperature the electrons easily jump to conduction band and also some electrons from valence band jump to conduction band. It makes the number of electrons more in conduction band than the number of holes in valence band. So conduction takes place due to electrons. Whereas the acceptor energy level EA lies slightly above the top of the valence band. At room temperature, many electrons of the valence band get excited to these acceptor energy levels, leaving behind equal number of holes in the valence band. These holes can conduct current. Thus, the valence band has more holes than the electrons in the conduction band.

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Navjot Kaur 6 years, 3 months ago

Sia is right.but to learn this there is a easy trick i.e." Father Mother Child".which is in order of " Thumb ,first finger & middle finger mutually perpendicular to each other "where Father =Force , Mother =Magnetic field & Child = Current or Charge.

Sia ? 6 years, 3 months ago

Fleming’s left hand rule states that stretch the forefinger, the central finger and the thumb of your left hand mutually perpendicular to each other. If the forefinger shows the direction of the magnetic field and central finger that of the current, then the thumb will point towards the direction of motion of the conductor.

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Srijan Kumar 6 years, 3 months ago

Because they are mixed together in a constant proportion

Srijan Kumar 6 years, 3 months ago

Because there constituents metals or non metallic properties improved due to chemical change
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Srishti Choudhary ✍⏳ 6 years, 3 months ago

Same here also guys..m bhi drop hi lungi...??
Same here mein bhi drop hi lungi......??

Priya Dharshini 6 years, 3 months ago

Understand concepts instead of mugging upneverything. Do ncert,read ncert. Practice all the derivations, most of the numericals,value based questions...... use guides to do these thing. Physics is tough subject for me also. I am trying my level best to score good
gud luck. ✌️. I will also give but I know without coaching it is impossible for me to crack but try Kerne mein Konsa kuch ja ra hai mera. .

Aman Kumar 6 years, 3 months ago

Such bolu...toh mujhse bhi dono nhi ho pa raha...Nd I have fear that if I focus on both then neither board will get clear not jee mains?...But I will try my best this year also?
I will drop for 1 year after 12th . As I realised that dono saath mein nhi ho payega. First I should concentrate on board then mai aiims and neet ka exam dungi.

Aman Kumar 6 years, 3 months ago

I want 2 ask dars..that this year u r preparing 4 neet or u want to take a drop???
to score gud marks in it we should work on our concept.. nd calculation to. make sure that ur numerical part is strong. prepare from ncert and refresher . Last five year question help lot to score 90 +.
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Sia ? 6 years, 3 months ago

Electric field intensity at a distance r from line charge of density {tex}\lambda {/tex} is
{tex}E = \frac{\lambda }{{2\pi {\varepsilon _0}r}}{/tex}
{tex}\therefore {/tex} Field intensity on negative charge (r = 0.02 m)
{tex}{E_1} = \frac{{4 \times {{10}^{ - 4}} \times 9 \times {{10}^9} \times 2}}{{0.02}} = 3.6 \times {10^8}N/C{/tex}
Force on negative charge
{tex}{F_1} = q{E_1} = 2 \times {10^{ - 8}}\left( {3.6 \times {{10}^8}} \right) = 7.2N{/tex}
It is directed towards the line charge.
Similarly field intensity at positive charge (r = 0.022 m)
{tex}{E_2} = \frac{{4 \times {{10}^{ - 4}} \times 9 \times {{10}^9} \times 2}}{{0.022}} = 3.27 \times {10^8}N/C{/tex}
Force on positive charge
{tex}{F_2} = q{E_2} = 2 \times {10^{ - 8}}(3.27 \times {10^8}) = 6.54N{/tex}
It is directed away from the line charge.
{tex}\therefore {/tex}Net force on the dipole,
F = F1 - F2 = (7.2 - 6.54)N = 0.66 N
F is towards the line charge.

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