logo

Ask Questions, Get Answers

 
X
 Search
Want to ask us a question? Click here
Browse Questions
Ad
0 votes

Two equal and opposite charges $ 8 \times 10^{-8} C$ are placed $ 2 \times 10^{-2} $ cm away from a dipole . If this dipole is placed in an external electric field $2 \times 10^8 N/C$. the value of maximum torque and work done in rotating through $180^{\circ}$ will be :

$(A)\;64 \times 10^{-4} Nm \;and\; 64 \times 10^4 J \\ (B)\;32 \times 10^{-4} Nm \;and\; 32 \times 10^{-4} J \\ (C)\;64 \times 10^{-4} Nm \;and\; 32 \times 10^{-4} J \\ (D)\;32 \times 10^{-4} Nm \;and\; 64 \times 10^{-4} J $

Can you answer this question?
 
 

1 Answer

0 votes
$z= PE \sin \theta = q (2l) E \sin \theta$
$Z_{max}= q(2l)E$
$\qquad= 8 \times 10^{-8} (2 \times 10^{-2} \times 10^{-2} ) \times 2 \times 10^8$
$\qquad= 32 \times 10^{-4}Nm$
$w= PE(1- \cos \theta) =q(2l) \in (1- \cos \theta)$
$\qquad= 8 \times 10^{-8} (2 \times 10^{-2} \times 10^{-2} ) 2 \times 10 ^{8} \times (1-(-1))$
$\qquad= 64 \times 10^{-4}J$
Hence D is the correct answer.
answered Jan 6, 2014 by meena.p
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...