Share Questions which are "not Hard but require Deep Thinking"

[Siddhant_Mudholkar]

@Sourav_Madanpuri I think height h will make a difference here. The question in my copy has hollow cylinder of same height as solid one. Btw what's the answer?

[Sourav_Madanpuri]

Ans is Mh ln(2)/πηR²

Use
dτ=Fr=-ηArdv/dy=-η2πR² ωr/h dr

Integrate it from 0 to R

Then use τ=Idω/dt

[Viraj]

A nice one.

[Siddhant_Mudholkar]

Not tough but different from mainstream problems answer written beside question

[pratyaksh_tyagi]

@Viraj answer is this ?

[Viraj]

No ..@pratyaksh_tyagi ..

Shud I share the answer ? Or wud like to give it a try ?

[pratyaksh_tyagi]

No I'll try

[Viraj]

Yeah @Siddhant_Mudholkar

[kunal_Deshmukh]

mr^2(meo×i1×i2)(1/m+r/MR)×1/2R
It is wrong probably

[Viraj]

Thats not the answer.. @kunal_Deshmukh ..

[kunal_Deshmukh]

Share ans

[kunal_Deshmukh]

I tried and have final ans want to check it so ......

[pratyaksh_tyagi]

Just tell me one thing, as r<<R so can the affect of the magnetic field of smaller loop be neglected ?

[kunal_Deshmukh]

As per my ans .No

[Sourav_Madanpuri]

@Viraj why it is mentioned r<<R. What's it's use/significance

[kunal_Deshmukh]

So that we can take magnetic field at centre for calculation of torque I think

[pratyaksh_tyagi]

It has nothing to do with r<<R

[kunal_Deshmukh]

For calculation of torque we find force
I L×B if the magnetic field is diff on each point
But here it is diff to calculate magnetic field by big loop at each point of small loop.so instead we take magnetic field at centre as radius is small it will not wary much
M×B

[Satyendra_Srivastva]

Planes of both coil are mutually perpendicular .
What do they mean by this line? It is this

Or if they released what happens then? @pratyaksh_tyagi
@kunal_Deshmukh @Viraj

[pratyaksh_tyagi]

Bro see , the magnetic field of outer loop is outwards at centre and it will exert a torque on smaller loop , And vice versa. ( same the smaller loop do , I.e .. rotate outer loop)
If you find initial torque using mB it will be greater for outer loop , which makes it complicated
@Satyendra_Srivastva assume current in same direction as it is not mentioned
The torque is function of theta which is different for both as the magnetic moment vectors and fields are shifting.
So try to imagine at some general angle theta and figger out, last time I used m b= i alpha to figger out relationship between the angles of both , but it didn't work