Ask questions which are clear, concise and easy to understand.

10 electric dipoles, each of dipole moment 10Cm, are located symmetrically inside a closed Gaussian surface. Calculate the electric flux of the surface.

Posted by Kashish Ahlawat (Jun 24, 2017 7:23 p.m.) (Question ID: 6157)

who to make and gate model

Posted by Ishant Kanojiya (Jun 24, 2017 9:10 a.m.) (Question ID: 6142)

A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90s,91s,92s & 95s. If the mimimum division in the measuring clock is 1s, then find the reported mean time ?

Posted by Saurav Kumar (Jun 23, 2017 10:02 p.m.) (Question ID: 6137)

• Let’s  first  find  the mean  value  of time:

{tex}t_{mean}={t_1+t_2+t_3+t_4\over 4}{/tex}

{tex}{90+91+95+92\over 4}= 92 {/tex}

Then,  we can  find  the  absolute error for each  measurement:

{tex}\Delta t_1=|t_{mean}-t_1|= |92-90|=2{/tex}

{tex}\Delta t_2=|t_{mean}-t_2|= |92-91|=1{/tex}

{tex}\Delta t_3=|t_{mean}-t_3|= |92-92|=0{/tex}

{tex}\Delta t_4=|t_{mean}-t_4|= |92-95|=3{/tex}

Let’s  calculate the mean  absolute error:

{tex}\Delta t_{mean}={ \Delta t_1+ \Delta t_2+ \Delta t_3+ \Delta t_4\over 4}{/tex}

{tex}{2+1+0+3\over 4}= 1.5{/tex}{tex}\approx 2{/tex}

Therefore,  the reported  mean  time should  be  92 ± 2s

Answered by Payal Singh (Jun 24, 2017 5:42 p.m.)
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Two metallic balls are charged and suspended by threads from the same point. The whole set up is taken to space where ther is no gravity. What is the angle between the threads and the tension in the string?

Posted by Ritika kohli (Jun 22, 2017 1:53 p.m.) (Question ID: 6099)

An electric charge A of strength 'q' exerts a force'F' on another similar charge B of strength 'q' separated by a distance 'r' in air.

(a) If a third charge C of strength '2q' is placed midway between the charges A and B, what is the force exerted by A on B?

(b) If the magnitude of each charge A and B is doubled and the charges are placed in a medium of relative permitivity 16, at a distance 1/2r, determine the force exerted by A on B?

Posted by Ritika kohli (Jun 22, 2017 1:51 p.m.) (Question ID: 6098)

What are the dimensions of permitivity of a medium?

Posted by Ritika kohli (Jun 21, 2017 10:57 p.m.) (Question ID: 6096)

• Dimensions of  {tex}\in{/tex} electrical permittivity of medium  is {tex}[M^{-1}L^{-3}T^4A^2].{/tex}

Answered by Payal Singh (Jun 22, 2017 8:15 a.m.)
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a 100w buld and 500w bulb are joined in parellel to mains which will draw more current.

Posted by satnam singh (Jun 21, 2017 12:26 p.m.) (Question ID: 6079)

• 500w bulb will draw more current.

Answered by Pfff Xy (Jun 22, 2017 9:31 p.m.)
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Is the glass is amorphous?

Posted by Nirmal Kumar (Jun 20, 2017 9:49 p.m.) (Question ID: 6060)

• The molecules then have a disordered arrangement, but sufficient cohesion to maintain some rigidity. In this state it is often called an amorphous solid or glass.

Answered by Payal Singh (Jun 20, 2017 10:49 p.m.)
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Is the concept of electric flux varies for a plane object and ring?

How?

Posted by Nirmal Kumar (Jun 20, 2017 9:48 p.m.) (Question ID: 6059)

Is the concept of electric flux varies for a plane object and a ring ?

How?

Posted by Nirmal Kumar (Jun 20, 2017 9:45 p.m.) (Question ID: 6058)

Derive an expression for the electric field due to a system of chages qand q2 with position vector rand rat a distance with respect to common origin.

Posted by Vikash Prajapati (Jun 20, 2017 4:52 p.m.) (Question ID: 6052)

a current i flows through a uniform wire of diameter d when the mean electron drift velocity is v .the same current flows through a wire of length d/2 made of same material if the mean drift velocity is________

Posted by Sakshi Muskan (Jun 19, 2017 2:12 p.m.) (Question ID: 6029)

Prove Gauss theorm for closed surface of asymmetrical shape?

Posted by Deep Kaur (Jun 19, 2017 11:38 a.m.) (Question ID: 6024)

How along non zero component unit test charge move

Posted by Annu Priya (Jun 17, 2017 12:43 p.m.) (Question ID: 5973)

What is capacitance of a conductor?

Posted by SIDDHANT GANGLY (Jun 13, 2017 8:05 p.m.) (Question ID: 5895)

• The measure of the ability of a conductor to store electric charge or energy is known as capacitance of a conductor.

OR

Capacitance of a conductor is the amount of charge that a capacitor can store per unit of potential difference.

C = q/V

Where, C stands for Capacitance

q stands for charge on a conductor

V stands for potential of the conductor

Answered by Ashutosh Kumar (Jun 14, 2017 7:55 a.m.)
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Why two equipotential surface are not interested?

Posted by Ankit Singh (Jun 11, 2017 12:11 p.m.) (Question ID: 5849)

• because two different equipotential surface have different electric potential, so if they intersect then the point of intersection will have two different potentials at the same point which is not possible.

Answered by Payal Singh (Jun 11, 2017 12:22 p.m.)
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'automobiles ignition failure occurs in damp weather.'   explain, why??

Posted by yatin jindal (Jun 08, 2017 1:18 p.m.) (Question ID: 5755)

• The insulating porcelain of the spark plugs accumulates a film of dirt. The surface dirt is hygroscopic and picks up moisture from the air. Therefore, in humid weather, the insulating porcelain of the plugs becomes quasi-conductor. This allows an appreciable proportion of the Spark to leak across the surface of the plug instead of discharging across the gap.

Answered by minakshi kapoor (Jun 08, 2017 5:09 p.m.)
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In filling the gasoline tank of an aeroplane, the metal nozzle of the hose from the gasoline truck is always carefully connected to the metal of the aeroplane by a wire, before the nozzle is inserted in the tank. explain why??

Posted by yatin jindal (Jun 08, 2017 1:16 p.m.) (Question ID: 5754)

•  The aeroplane and the gasoline truck usually have wheels with rubber tyres, they are insulated from the ground. Further, the service ramps are usually made of concrete and are not necessarily good conductors to the earth. Therefore, inspite of grounding metallic ropes, the aeroplane and the truck could remain charged.A spark may jump and ignite the explosive gasoline, when the metal nozzle is brought near the aeroplane. The connection of metal of the aeroplane and the nozzle of the hose with a wire avoids any unbalance of charge and hence the risk of gasoline.

Answered by minakshi kapoor (Jun 08, 2017 5:11 p.m.)
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A pendulum bob of mass 80mg carrying a charge of 2 * 10-8 C is at rest in a horizontal uniform electric field of 2*10Vm-1.Find the tension in the thread of the pendulum and the angle it makes with the vertical.

Posted by Vishnumaya Menon (May 31, 2017 7:35 p.m.) (Question ID: 5604)

• Given: mass = 80 mg = 80 × 10-6 Kg

Charge q = 2 × 10-8 C

E = 2 × 104 Vm-1

Let T is tension in string and {tex}\theta{/tex}

is angle of string with vertical.

In equilibrium

{tex}Tsin\theta = qE \ ....(1){/tex}

{tex}Tcos\theta = mg \ ....(2){/tex}

Divide (1) by (2), we get

{tex}tan\theta = {qE\over mg}{/tex}

=> {tex}tan \theta = {2\times 10^{-8}\times 2\times 10^4\over 80\times 10^{-6}\times 10}{/tex}

=> {tex}tan \theta = 0.5{/tex}

=> {tex}\theta = 27^°{/tex}

Now Tension T = {tex}qE\over sin \theta{/tex}{tex}{2\times 10^{-8}\times 2\times 10^4\over sin 27^°}{/tex}

= 8.8 × 10-4 N

Answered by Payal Singh (Jun 01, 2017 3:43 p.m.)
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what is drift velocity

Posted by praful singh (May 27, 2017 10:55 p.m.) (Question ID: 5525)

• The drift velocity is the average velocity that a particle, such as an electron, attains in a material due to an electric field. It can also be referred to as axial drift velocity.

In general, an electron will propagate randomly in a conductor at the Fermi velocity

Answered by Payal Singh (May 28, 2017 9:52 a.m.)
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Name the dielectric  whose molecules have zero and non zero dipole moment.

Posted by Shubhanshu Shubh (May 20, 2017 4:24 p.m.) (Question ID: 5396)

• (i) The dielectric having non- zero dipole moment is water.

(ii) The dipole having zero dipole moment is diamond (or silicon).

Answered by Payal Singh (May 20, 2017 4:35 p.m.)
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Two charges of 2microC but opposite in sign are placed 1pcm apart.Calculate the electric field at a point distance 10cm from the midpoint on the axial line of dipole.

Posted by Vishnumaya Menon (May 20, 2017 9:56 a.m.) (Question ID: 5388)

• Ans. Given :

Charge q = 2 mC = {tex}2 \times 10 ^{-6} C{/tex}

Distance b/w them (2a) = 10 cm = 10-1 m

Distance from mid-point on axial line r = 10 cm = 10-1  m

We Know

p = {tex}q \times 2a{/tex} = {tex}2 \times 10 ^{-6} \times 10^{-1} = 2 \times 10 ^{-7} {/tex}

Electric field due tp dipole on Axial line E  = {tex}{1\over 4\pi \in } \times {2p\over r^2}{/tex}

{tex}9\times 10 ^ 9 \times 2 \times 2 \times 10^{-7}\over 10^{-2} {/tex} = {tex}36 \times 10 ^ 7 \ N/C{/tex}

Answered by Naveen Sharma (May 20, 2017 10:16 a.m.)
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Using Gauss Law, show that electric field inside a conductor is zero.

Posted by Yogendra Singh (May 09, 2017 4:48 p.m.) (Question ID: 5172)

Is there some method of charging a conductor without rubbing it with another object and without bringing it into contact with a charged body?

Posted by Nahla Saman (May 07, 2017 8:15 p.m.) (Question ID: 5152)

• Yes method of induction.

Just bring the charged body closer to another uncharged body,

Induction charging is a method used to charge an object without actually touching the object to any other charged object.

Answered by Payal Singh (May 07, 2017 10:53 p.m.)
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Equal charges each of 20 meucoulumb are placed at x=0,2,4,8,16cm on X- axis . find the force experienced by the charge at x=2cm?

Posted by Raima Rakshit (May 05, 2017 10:19 p.m.) (Question ID: 5130)

• but  the ans given in the book is 1.2 X 10N

Posted by Raima Rakshit (May 06, 2017 10:15 p.m.)
• Solution:

Let q1,q,q,qand q be the charges at x = 0,2,4,8,16 on x-axis.

Let F be the resultant force.

F1 - Force on q2 due to q1

F3 - Force on q2 due to q3

F4 - Force on q2 due to q4

F5 - Force on q2 due to q5

F = F1+F3+ F4+ F5

F = {tex}k {q_1q_2\over (r_{21})^2} + k {q_3q_2\over (r_{23})^2}+ k {q_1q_4\over (r_{24})^2}+ k {q_1q_5\over (r_{25})^2}{/tex}

{tex}F = k {qq\over (r_{21})^2} + k {qq\over (r_{23})^2}+ k {qq\over (r_{24})^2}+ k {qq\over (r_{25})^2}{/tex}

[q1=q2 =q3 =q4 = q = q = {tex}20\times 10^{-6} C{/tex}]

{tex}F = k {q^2\over (r_{21})^2} + k {q^2\over (r_{23})^2}+ k {q^2\over (r_{24})^2}+ k {q^2\over (r_{25})^2}{/tex}

{tex}F = k q^2\left[{1\over (r_{21})^2} + {1\over (r_{23})^2}+ {1\over (r_{24})^2}+ {1\over (r_{25})^2}\right]{/tex}

{tex}r_{21} = 2cm = 2\times 10 ^{-3}m\\ r_{23} = 2cm = 2\times 10 ^{-3}m \\ r_{24} = 6cm = 6\times 10 ^{-3}m\\ r_{25} = 14cm = 14\times 10 ^{-3}m{/tex}

Putting values of all, we get

{tex}F = 9\times10^9 \times 20\times 10^{-6}\left[{1\over (2\times 10^{-2})^2} + {1\over (2\times 10^{-2})^2}+ {1\over (6\times 10^{-2})^2}+ {1\over (14\times 10^{-2})^2}\right]{/tex}

F = {tex}1.92\times 10^4 N{/tex}

Answered by Payal Singh (May 09, 2017 9:18 a.m.)
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Two charges +q and -q are kept at (-x2,0) and (x6,0) respectively in the x-y plane. Fond magnitude and direction of net electric field at organ (0,0)

Posted by Abdurrehman Faris (May 03, 2017 9:17 p.m.) (Question ID: 5102)

The RMS value of the electric field of the light comimg from the sun is 720N/C. The average total energy density of electomagnetic wave is

Posted by Aishwarya Ayitha (Apr 28, 2017 2:25 p.m.) (Question ID: 5055)

What are the combinations of NOR & NAND gate

Posted by Aashka Shah (Apr 25, 2017 2:26 p.m.) (Question ID: 5033)

• no , I am asking their combinations like

2 NAND gate makes

3 NAND gate makes which gate

same as NOR

2NOR , 3 NOR

Posted by Aashka Shah (Apr 27, 2017 10:04 p.m.)
• what their combinations are called

Posted by Aashka Shah (Apr 25, 2017 5:50 p.m.)
• They themselves are the combinations

NOR GATE-OR GATE + NOT GATE

NAND GATE- AND GATE + NOT GATE

Answered by raghav aggarwal (Apr 27, 2017 1:26 p.m.)
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What is POYNTING VECTOR ?  &

What does it represent ?

Posted by Aashka Shah (Apr 24, 2017 11:46 p.m.) (Question ID: 5031)

• In physics, the Poynting vector represents the directional energy flux density (the rate of energy transfer per unit area) of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m2).

The Poynting vector is defined as

<dl> <dd></dd> </dl>

where

• E is the electric field vector;
• H is the magnetic field's auxiliary field vector.
• S is Poynting vector
Answered by Shweta Gulati (Apr 25, 2017 1:07 p.m.)
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When a wire of resistance R is streched and its radius becomes r/2 , then new resistance is ?

Posted by Aashka Shah (Apr 24, 2017 6:07 p.m.) (Question ID: 5026)

• Ans. Let the Initial Length of Wire = l

Final length of Wire = L

Intial Radius of wire = r

FInal Radius of Wire r1 = {tex}r\over 2{/tex}

So, Initial Volume of Wire = Final Volume of Wire

{tex}=> \pi r^2 l = \pi r_1^2L{/tex}

{tex}=> r^2 l = ({r\over 2})^2L{/tex}

{tex}=> r^2 l = {r^2\over 4}L{/tex}

{tex}=> L = 4l{/tex}

Initial Area of Cross Section of wire (A) = {tex}\pi r^2{/tex}

Final area of Cross section of wire (A') = {tex}\pi r_1^2 = \pi{r^2\over 4}{/tex}

Initial Resistance of Wire (R)= {tex}\rho {l\over A} = \rho {l\over \pi r^2}{/tex}

Final Resistance of Wire (R') = {tex}\rho {L\over A'} = \rho {4l\over {\pi r^2\over 4}} ={ \rho 4\times 4l\over\pi r^2}{/tex}

{tex}16\rho{l\over \pi r^2} = 16R{/tex}

So new Resistance ll be 16 times of initial Resistance.

Answered by Naveen Sharma (Apr 25, 2017 3:54 p.m.)
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