Applied Physics 2 Tutorial (XXXXX)
College of Technology (COLTECH)
Semester: Second Semester
Level: 200
Year: 2015
THE UNIVERSITY OF B AMENDA
COLTECH
Applied Physics 2
Tutorial 1
1) An -particle in the nucleus of a helium atom has a mass m = 6,64x1 O
-27
kg
and charge q =+2e (e is the electronic charge). Compare the electrostatic
repulsion between 2α- particles with the gravitational force of attraction
between them. Comment on whether the gravitational force is larger than
the electrostatic force
2) A force of 0.2N is exerted by a positive charge, - mc on another charge q,
placed at distance of 20cm away. What is the magnitude and nature of the
charge q?
3) Two charges separated by a distance of 0.5cm attract each other with a
force of 10'
3
N. What will be the distance between them if the force of
attraction must be 10
-5
N?
4) The walls of the membrane of a body cell carry a negative ion (-e) on the
inside and a positive ion (+e) on the outside. The walls are separated by
distance of 8 A
(1 A
=10
-10
).
a) If space between walls is assumed to be made up of air, what is the
electrical force between the ions?
b) If the dielectric constant of the cell membrane is 8, what will be the force
calculated in (a)?
5) Each of 2 small spheres is positively charged, the combined charge totaling
4x 10
-8
C. What is the charge on each sphere if they are repelled by a force of
2.7 x l0
-4
N when separated by distance 10cm?
6) Two point charges are located in the xy place such that charge q = 2 x 10
-9
C
is at point (x =0, y = 4cm) and charge q2 = - 3 x 10
-9
C is at point (x = 3cm , y =
4cm ). A third charge q3 = 4 x 10
-9
C is placed at the origin of the axis.
a)
Find the x & y components of the total force on this charge
b)
Find the magnitude and direction of the total force calculated in a
7) Point changes of magnitude 2x 10
-9
C (all positive are situated at each of 3
corners of a Square of sides 0.2m). Find the magnitude and direction of the
resultant force on a point charge – 1 x 10
-9
C if it were placed
a)
At the Centre of the square
b)
At the 4
th
corner of tire square
8) Two small balls each of mass 15g are attached to silk threads 0.3, long and
hung from a common point. When the balls are given equal quantities of
negative charge, each thread makes an angle of 20°B with the vertical.
a)
Find the magnitude of the charge of each ball.
b)
The 2 threads are then shortened to 0.5, while maintaining the charge on the
balls. What angle does each thread make with the vertical?
?) An electric charge is distributed uniformly along a lone of length a, lying
along the y axis. A point charge, -q lies on the x-axis at a distance x from the
origin. Find the total force exerted on q.
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