Download proton 8x106 ms

Homework 1
Charges & Electric Fields
Mass of electron
9.11x10-31 kg
Charge on electron
-1.6x1019 C
Mass of proton
1.673x10-27 kg
Charge on proton
1.6x1019 C
Mass of neutron
1.675x10-27 kg
Charge on electron
0C
1. Draw a diagram showing the electric field in each of the following:
(a) around a positive point charge
(b) between a positive point charge and a negative point charge
(c) between a positive flat plate and a negative flat plate
2. Calculate the work done on a proton which is placed in a 3kV electric field.
3. In a particle accelerator, electric fields are used to accelerate sub atomic particles. By equating
work done and kinetic energy, find the velocity of each of the following when placed in a 14kV
electric field, assuming the particles are initially at rest.
(a) a proton
(b) an electron
(c) an alpha particle (2 protons and two neutrons)
4. Calculate the voltage of electric field required to accelerate an electron from rest to 6% of the
speed of light in a vacuum.
5. Two opposite charged plates are set up as shown and a proton is fired into the field from the left
through a small hole in the plate at a velocity of 8x106 ms-1. The electric field has a voltage of
6kV. Calculate
(a) the work done on the proton by the electric field
(b) the initial kinetic energy of the proton when it enters the field
(c) the total energy of the proton when it reaches the negative plate
(d) the velocity of the proton on reaching the negative plate
(e) the average force acting on the proton while in the electric field.
Hint: Equate the work done (Ew=Fd) with the work done by the electric field
1.
+
+
+
+
-
proton
8x106 ms-1
+
+
+
+
1.3m
Homework 2
Charges & Electric Fields 2
1. For each of the arrangements of point charges shown, calculate the direction and magnitude
of the force acting on charge x.
(a)
+5.0μC
(b)
+3.0μC
X
7 cm
(c)
+5.0μC
+3.0μC
X
-2.5μC
5 cm
-1.8μC
X
5 cm
4 cm
+4.0μC
2. For the arrangement of charges in 1(a), calculate the electric potential at a point 3cm to the
right of the 5μC charge.
3. For the arrangement of charges in 1(b), calculate the magnitude of the electric field strength
at a point 5 cm directly above the 3μC charge.
4. Electrons are accelerated in a CRT to a relativistic velocity of 8.0x107ms-1. Calculate
(a) The total relativistic energy of the electron at this velocity
(b) The kinetic energy gained by the electron assuming it was initially at rest
(c) The p.d. between the cathode & anode required to accelerate electrons to this velocity
5. Electrons moving at 8.2x106 ms-1 are fired between deflection plates. The plates produce a
uniform electric field. The deflection plates are set up 1cm apart and are charged to a
voltage of 60V. The plates have a length of 2cm. Calculate:
(a) The electric field strength between the plates.
(b) The vertical acceleration of an electron in the field
(c) The total time the electron spends in the field
(d) The deflection angle of the electron beam
6. An alpha particle is fired at a velocity of 6.0x106 ms-1 at an atom of gold (atomic number 79).
Assuming the alpha particle approaches the nucleus directly, how close will the alpha
particle get to the gold nucleus?
Homework 3
Magnetic Fields and Magnetic Induction
1. Calculate the magnitude and direction of the force experienced by the wire marked ‘A’ in
each of the following arrangements of conductors and externally applied magnetic fields
(a)
(b)
0.6 m
0.85 m
Current = 3.2 A
Wire A
Current = 2.0 A
0.15 m
Wire A
Current = 6.0 A
Mag. Field Strength = 0.45 T
(c)
Wire A
(d)
1.6 m
1.2 m
23º
Current = 6.2 A
75º
Current = 7.3 A
Wire A
Mag. Field Strength = 0.062 T
Mag. Field Strength = 0.32 T
2. Calculate the magnitude of the force acting on an electron moving at 3% of the speed of
light perpendicular to a magnetic field of 0.046 T. Hence calculate the radius of its circular
path.
3. Explain how a velocity selector can use a combination of magnetic and electric fields to
produce a stream of particles with a constant known velocity. Use a diagram in your answer.
4. A proton is fired into a 0.38 T magnetic field at an angle of 24º to
the field and a velocity of 1.4x107 ms-1 as shown. Calculate:
(a) The magnitude of the force experienced by the particle.
(b) The radius of the helical path followed by the proton.
(c) The period of its rotation
(d) The horizontal distance travelled in one rotation
Path of proton
24º