History/Concepts
State a difference between an AC motor and a DC motor.
AC motor = slip ring
DC motor = split ring
Calculate the electric field given the potential difference is 120V and the distance between two plates is 0.150cm.
E = V/d
E = 120/ 0.0015
E = 80 000 V/m
U238 becomes U235
How many neutrons are released during nuclear fission?
3
Which spectra is used for;
LIGHT
FOG
Light - emission spectra
Fog - absorption spectra
Give the name of the law which states;
The radius affects the orbital period.
Kepler's Third Law
Identify the scientist(s)
Alpha particle hits the nucleus and deflect as a result of the proton.
Some of the alpha particles pass through as the atom is primarily empty space.
Greiger Marsden
Rutherford
Calculate the power lost in a transformer which has 4A of current and experiences a resistance of 2Ω.
P loss = I2 R
P loss = (42) (2) = 32 Watts
Calculate the torque given each a coil when each side is 3cm and the magnetic field is 0.5T with a current of 2A
Torque = nAIB Sin Ꝋ
Torque = (1)(0.009)(2)(0.5) Sin 90
Torque = 0.009 N/m
According to Faraday's Law a moving magnet will induce a _______________-
current
The ratio r3/T2 is constant (k) for all the planets orbiting the same central M______
Same central mass (Sun)
Broad lines in an ABSORPTION SPECTRA represents;
- a D__________ object
- a R__________ object
Rotating object
A 300 KW transformer reduces voltage to 120V and experiences a resistance of 2Ω/km.
Calculate the current required
P = VI
I = P/V
I = P/V = 300 000 / 120 = 2500A
Calculate the current experienced in the loop given the magnetic field is 2T and the torque is 5 N/m with the side lengths been 3cm and 7cm.
Torque = nAIB Sin Ꝋ
I = Torque / nAB Sin Ꝋ
Torque = nAIB Sin Ꝋ
I = Torque / nAB Sin Ꝋ
I = 5 / (1)(0.03 x 0.07)(2)
I = 1190.5 A
An increase in the frequency of light caused electrons to be released from the metal.
The greater the frequency the higher the kinetic energy of the electrons.
Identify the name given to this phenomena.
Photoelectric effect
Magnetic flux is the ________________
strength and direction of a magnetic field.
Stated that electrons do not move in set paths but rather occupy spaces called ORBITALS.
SCHRODINGER
Given the mass of an electron is 9 x 10^-31 kg
Calculate the acceleration by the electron.
E = 80 000 q = 1.6 x 10^-19 C
a = F/m a = qE /m
F = ma
F = qE
a = F/m a = qE /m
a = 80 000 (1.6 x 10^-19)/(9 x 10^-31)
Calculate the gravitational potential energy for a 3000kg GEO satellite which occupies an altitude of
35 000 km.
U = -GMm/r
U = -GMm/r
U = (6.67 x 10^-11)(5.97 x 10^24)(3000) / (6731 x 10^3m + 35 000 000)
U = - 2.86 x 10^10 J
Positive current is induced when
The ________ part of a magnetic moves into a coil.
Negative current is induced when
The ________ part of a magnetic moves into a coil.
North part
a)____ shift occurs when objects move away and b) ______ shift occurs when objects approach.
a) Red shift
b) Blue shift
Distinguish between Relativistic Mass and Invariant Mass.
Relativisitic mass changes in response to velocity and speed. Relativistic mass is energy.
Invariant mass is not affected by velocity.
Calculate the binding energy for HELIUM given the mass defect is 0.03002 amu and c is representative of 931.5 MeV.
E = (0.03002)(931.5)
E = 27.96 MeV E = 7MeV
Calculate the binding energy for LITHIUM given the mass defect is 0.11829 amu and c is representative of 931.5 MeV.
Binding energy E = mc2
E = (0.11829)(931.5)
E = 110.187 MeV
E = 110.187/7 = 15.71 nucleon
Identify a component of a transformer core that reduces energy loss due to eddy currents.
Laminated varnish covering the core.
Eddy currents cause energy loss in the transformer. How can we reduce the energy loss?
Increase the resistance using a laminated varnish