1
A
B
C
Which one of the following statements is FALSE?
In mechanics, all frictionless processes are irreversible.
Dissipative processes are irreversible.
Heat energy is not a distinct energy type.
D
E
Energy transfer between a system and its surroundings that is not a heat transfer is called
work.
Heat and work are not state functions.
2
A
B
C
D
E
Which one of the following quantities is NOT an extensive parameter?
mass
heat
volume
entropy
temperature
3
A
Which statement is CORRECT for the first principle of thermodynamics?
The total amount of energy of an isolated system is increasing.
B
C
D
E
It is an extension of the energy conservation principle on systems which are in thermal
equilibrium with their environment.
The change of the internal energy is equal to the product of the work and the heat.
It is possible to build a first kind of perpetuum mobile.
The change of the internal energy is equal to the ratio of the work to the heat.
4
A
B
C
D
E
If pressure and enthalpy are constants, the criterion for spontaneous process is…
entropy (S) increase; ΔS > 0
internal energy (U) decrease; ΔU < 0
Gibbs free energy (G) decrease; ΔG < 0
Helmholtz free energy (F) decrease; ΔF < 0
temperature (T) increase; ΔT > 0
5
A
B
C
D
E
Which one of the following statements is CORRECT?
In isolated systems, there can be energy transfer to the environment.
In closed systems, reversible processes increase the entropy.
Everything that does not belong to the system is called environment.
The intensive quantities are additives.
Dissipative processes are irreversible.
6
According to Coulomb’s law:
A
the force between two point charges is directly proportional to the charge of the individual
point charges, and inversely proportional to the square of the distance between them.
B
the force between two point charges is directly proportional to the charge of the individual
point charges, and inversely proportional to the distance between them.
in a closed system, the algebraic sum of electric charges remains constant.
C
E
the force between two point charges is directly proportional to the squared charge of the
individual point charges, and inversely proportional to the distance between them.
current intensity is equal to the number of charges transported over unit time.
7
What defines the electric field vector?
A
The force acting on a unit positive test charge.
B
The electric potencial of a unit negative test charge.
C
The work done on a unit positive test charge when moved to infinity.
D
The power of a unit negative test charge when moved to infinity.
E
The work done by a unit positive test charge when moved to infinity.
8
A
B
C
D
E
The electric field within a cavity inside a conducting material...
is zero, according to the Faraday-cage principle.
only depends on the total charges within the cavity, according to Coulomb’s law.
is infinite.
changes in a harmonic fashion with time.
is circularly symmetric due to the Lorentzian force.
9
A
B
C
D
E
The force acting on a point charge in an electric field is equal to...
the product of the electric field and the charge of the point charge.
the ratio of the electric field to the charge of the point charge.
the product of the electric flux and the charge of the point charge.
the ratio of the electric flux to the charge of the point charge.
the product of the electric current and the charge of the point charge.
10
A
B
C
D
E
For plate capacitors it is TRUE that...
their capacitance is proportional to the distance between the plates.
their capacitance is inversely proportional to the area of the plates.
the charge on the plates is proportional to the voltage.
their capacitance is proportional to the square of the distance between the plates.
their capacitance is inversely proportional to the square root of the area of the plates.
D
11
A
C
D
E
What does Ohm’s law state? (R – resistance, I – current, U – voltage)
R = I/U
The voltage (or potential difference) between two points of a conductor is proportional to
the current that flows through the conductor. The factor of proportionality is called
resistance.
The reciprocal value of resistance is called conductivity.
The number of charges is inversely proportional to the square of the electric resistance.
The reciprocal value of specific resistance is called specific conductivity.
12
A
Which one of the following statements is CORRECT?
In an alternating electric circuit, current intensity and voltage are always in phase.
B
The net resistance of the resistors in series is the reciprocal value of the sum of the
reciprocals of the individual resistances.
C
In case of stationary current, the sum of the currents flowing into the junction equals the
product of the currents flowing out of the junction.
D
The net resistance of the resistors in parallel is the reciprocal value of the sum of the
reciprocals of the individual resistances.
E
In case of stationary current, the sum of the currents flowing into the junction equals the
ratio of the currents flowing out of the junction.
13
A
B
C
D
E
Which one of the following statements is TRUE for induced voltage?
The voltage induced in a coil is directly proportional to the rate of the change of flux.
The voltage induced in a coil is inversely proportional to the rate of the change of flux.
The voltage induced in a coil does not depend on how fast the flux changes.
The voltage induced in a coil only depends on the number of windings.
The voltage induced in a coil only depends on the material of the coil.
14
A
B
C
D
E
What effects does electric current NOT have?
heat effect
magnetic effect
chemical effect
light effect
gravitational effect
15
A
Which formula is NOT correct for electric power? (P - power, U - voltage, I - current, R resistance, W - electric work, t - time)
P = U·I
B
P = U2/R
C
P = I2·R
P = U/I
P = W/t
B
D
E
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2
3
4
5
6
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9
10
11
12
13
14
15
A
E
B
A
C
A
A
A
A
C
B
D
A
E
D