સમાન મૂલ્ય \(0.01\,C\) ના અને \(0.4\,mm\) અંતરે રાખેલા બે વિદ્યુતભારો, વિદ્યુત ડાયપોલ (દ્વિધ્રુવી) ની રચના કરે છે. જો દ્રી-ધ્રુવીને \(10\,dyne/C\) ના નિયમિત વિદ્યુતક્ષેત્ર \(\vec{E}\) માં, \(\vec{E}\) સાથે \(30^{\circ}\) ના કોણે મૂકવામાં આવે, તો દ્વિ-ધ્રુવી પર લાગતા ટોર્કનું મૂલ્ય ...... હશે.

A \(4.0 \times 10^{-10}\,Nm\)
B \(2.0 \times 10^{-10}\,Nm\)
C \(1.0 \times 10^{-8}\,Nm\)
D \(1.5 \times 10^{-9}\,Nm\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(2.0 \times 10^{-10}\,Nm\)

Step-by-step Solution

Detailed explanation

\(|\overrightarrow{ P }|= qd\) \(=0.01 \times 0.4 \times 10^{-3}\) \(=4 \times 10^{-6}\) \(|\vec{\tau}|=\operatorname{PE} \sin \theta\) \(=4 \times 10^{-6} \times 10 \times 10^{-5} \times \sin 30\) \(=4 \times 10^{-6-5+1} \times \frac{1}{2}\) \(=2 \times 10^{-10}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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