<h2>Given :</h2>
- total charge = 9.0 mC = 0.009 C
Each electron has a charge of :

For producing 1 Cuolomb charge we need :
Now, for producing 0.009 C of charge, the number of electrons required is :
_____________________________
So, Number of electrons passing through the cross section in 3.6 seconds is :

Number of electrons passing through it in 1 Second is :
Now, in 10 seconds the number of electrons passing through it is :
_____________________________

Answer:
(a)The work done by the man is -15.03J.
(b)The force exerted on the object is 127.4N.
Explanation:
Mass of the object pulled by the man is -13kg
Object is lifted 11.8 cm vertical with his teeth it means (displacement = +11.8cm = +0.118m)
Acceleration due to gravity is 
(a) <u>Calculating the work done</u>:
Work done = mgh
Where "m" is mass of an object, "g" is acceleration due to gravity and "h" is the displacement.


The work done by the man is -15.03J.
(b) <u>Calculating the force</u>:
Probably the man and the object are close to the exterior of the earth. If the rigidity required to maintained the object of consistent velocity interior the gravitational field of the earth is 
Thus the weight of the object is balanced by the force of the man's teeth on the object. That is
F = mg

F = 127.4N
The force exerted on the object is 127.4N.
Answer:
28.57 cm
Explanation:
We are given that
Focal length,
Distance of application from his eyes,s=40 cm




s=25 cm
Substitute the values



