When an electric dipole of moment \(\left| P \right| \) = q \(\times\) 2a is held at an angle \(\theta\), with the direction of uniform external electric field E, a torque \(\tau \) = pE sin\(\theta\) acts on the dipole. This torque tries to align the electric dipole in the direction of the field. When p is along E, \(\theta=0^{o}\), \(\tau \) = pE sin\(0^{o}\) = zero.

Read the above passage and answer the following questions. 
(i) What is the direction of torque acting on an electric dipole held at a angle with uniform external field?
(ii) An electric dipole of length 10 cm having charge \(\pm 6\times { 10 }^{ -3 }\), C placed at \(30^{o}\) with respect to a uniform electric field experiences a torque of magnitude \(6\sqrt { 3 } \) N-m. Calculate magnitude of electric field.
(iii) What is the physical significance of this concept in our day-today life?

Two persons are standing under a tree and another person near them is inside a car. They were arguing about going out for a movie or to the beach, when a lightning struck the tree with some force. The person inside the car notices his friends satnding under the tree are affected by lightning, he comes out and takes them to the nearby hospital.
Why the person in the car was not affected by lighting?
What quality do you find the person inside the car?
Explain the process that takes place during lighting.
If the total charge enclosed by a surface is zero, then what will be the electric flux over the surface?

The surface integral of electrostatic field E produced by any source over any closed surface S enclosing a volume V in vacuum, i.e. total electric flux over the closed surface S in vacuum is \(1/{\epsilon}_{0}\) times the total charge Q contained inside S, i.e.
\({\phi}_{E}=\oint E.dS={{Q}\over{{\epsilon}_{0}}}\)
The charges inside S may be point charges or even continuous charge distributions. There is no contribution to "total electric flux from the charges outside S. Further, the location of Q inside S does not affect the value of surface integral.
Read the above passage and answer the following questions
What are the SI units and dimensions of electric flux?
A closed surface in vacuum encloses charges -q, + 3q and +5q. Another charge + 4q lies outside the surface. What is total electric flux over the surface?
A point charge a lies inside a spherical surface of radius r. How will the electric flux be affected, if, radius of the sphere is doubled?
What values of life do you learn from this theorem?

An old woman who had suffered from a heat stroke was taken to the hospital by her grandson who is in class XII. The grandson has studied in Physics that, how to save person who is suffering from a heat stroke, regular beating of the heat is to be restored by delivering a jolt to the heart using a defibrillator, whose capacity is 70 μF and charged to a 'potential of 5000 V and energy stored is 875 J, 200 J of energy is passed through a person's body in a pulse lasting 2 ms. The old woman gets paniced and refuses to be treated by defibrillator. Her grandson then explained to her the process that would be adopted by medical staff and how the result of that would bring her back to normalcy. The woman was then treated and was back to normal. Answer the following questions based on the above information.
(i) What according to you are the values displayed by the grandson?
(ii) What will be the net charge of the capacitor in defibrillator?

A man travelling in a car during heavy rain and thunderstorm, sees a boy standing under a tree. He immediately stops his car and asks the boy to get inside the car and saves him from a possible natural calamity. Answer the following questions based on the above information.
(i) What danger did the boy had while standing under the tree during the thunderstorm?
(ii) How is it safer inside the car during such weather?
(iii) What according to you are the values displayed by the man to help the boy?
(iv) Give another example from everyday life situations which represent display of similar values.