Fysisk

Question 1

Aspecific property of the characteristic x-ray radiation is its:

Answer 1

Reduction to a small number of narrow bands of wavelength (Spectral lines).

Question 2

A body is in a circular uniform motion at a speed of 100 m x s-1. Its trajectory is a circle with a radius of 3.00m. What is the frequency of this circular motion?

Answer 2

5.31 Hz

Question 3

Which of the following particles cannot be (after initial acceleration) set in circular motion by a homogeneous magnetic field?

Answer 3

Neutron

Question 4

Choose the true statement about sound and ultrasound. (Their sources are in rest in relation to the ambient medium.)

Answer 4

Ultrasound can travel by both transverse and longitudinal waves in solids

Question 5

A metallic bar of 100 mm2 cross-section area becomes longer by 0,10% due to action of 10 kN force. What is the coefficient (modulus) of elasticity of the metal the rod is mad of?

Answer 5

100 GPa

Question 6

If we change the term φ (i.e. the inital phase angle) in the equation describing the displacement y of a harmonically oscillating body, the oscillating body displacement y can reach its maximum value (the amplitude). Such a change of φ equals for any y for example:

Answer 6

No answer is correct

Question 7

A guided missile of 500kg fires for 5.00s its rocket engine which exerts a constant thrust force of 10.0 kN. How much will the speed of the missile change? (The procedure happens in vacuum and state of weightlessness; the missile mass does not change):

Answer 7

100m x s-1

Question 8

Which of the following units is only a number (i.e. belongs to a dimensionless quantity)?

Answer 8

Radian

Question 9

The NP and PN junctions in series form a semiconductor circuit element functioning as:

Answer 9

No answer is correct

Question 10

A weather balloon of 12.0 m3 volume and 10.0kg mass (Incl. the gas inside) ascends normally upwards under windless conditions at a constant velocity of 2.00 m.s-1. What is the net force exerted on the balloon against the direction of its movement? (air density is 1.00 kg x m-3, gravitational field or acceleration ag= 10.0 m.s-2)

Answer 10

1.20N

Question 11

One of the following sets of units contains only base (fundamental) and/or derived SI units.

Answer 11

Kelvin, candela, minute, radian, gram

Question 12

The pressure of an ideal gas increased three-times during an isothermal process in a vessel closed by a movable piston. It resulted in:

Answer 12

Decrease of its volume by the factor of 3

Question 13

Find a thermodynamic process during which no mechanical work can be done (ideal gas amount dos not change)?

Answer 13

Isochoric (or isosteric)

Question 14

The electric motor of a crane in a container transshipment point has a power of 200 kW. The container moves upwards at a constant speed of 2.00 m.s-1. What is the force exerted by the motor on the lifted container?

Answer 14

200kN

Question 15

There are three identical capacitors, each of 300 nF capacitance. What can be the resulting capacitance if we wire them in all possible combination ways (in series, in parallel or in another combination)?

Answer 15

600nF

Question 16

The isotopes of carbon differ in:

Answer 16

number of neutrons in the nucleus

Question 17

A sound of 1 kHz frequency has at a given place an intensity value of 10(-6) W.m-2. What is the sound level of this sound (consider the value of threshold sound intensity I0= 10(-12) W.m-2)?

Answer 17

60.0dB

Question 18

A body is thrown normally upwards directly from the surface of a small planet (ag= 3.00 m.s(-2), and reaches maximum altitude of 6.00 m. What is the initial speed of this body? (The plants has no atmosphere):

Answer 18

6.00 m.s(-1)

Question 19

Table-tennis balls are ascending at a constant speed towards the water surface (they were released by a diver some meters below the water surface). We suppose that the balls are under the action of buoyancy. We can say that the force of buoyancy during the ascent (the balls are considered incompressible):

Answer 19

Decreases

Question 20

Which of the following units is correctly substituted by a combination of other units?

Answer 20

Watt (J.S-1)

Question 21

The so-called de Broglie matter waves:

Answer 21

Characterise the wave properties of particles

Question 22

The constant direct current flowing through a resistor is 50.0 mA at voltage of 5.00 V. What is the time necessary for the transfer of 3.00 C electric charge?

Answer 22

60.0 s

Question 23

It is possible to place a steel needle on the water surface, and the needle will not sink. One of the following phenomena can be axplained on similar basis:

Answer 23

capillary depression

Question 24

The light rays travelled towards a lens with dioptric power of -8 D parallelly with its principal axis. What is the distance (measured from the centre of the lens) of the single point in which the rays (really or virtually) intersect?

Answer 24

12,5cm

Question 25

The unit of luminous flux is:

Answer 25

No answer is correct

Question 26

Two heavy spheres hanging on long ropes, which centres were originally in distance of r= 40cm, have changed their mutual position in such a way that their centres are in distance of r= 20cm now. The force of gravity acting between the spheres increased by factor of:

Answer 26

4

Question 27

Two close parallel wire carrying electric currents of the opposite direction are:

Answer 27

Repulsed

Question 28

Pure water becomes ice at a temperature different from 0 Celsius. This phenomenon is probably caused by:

Answer 28

changed (not normal atmospheric) external pressure

Question 29

29.In some hypothetical physical process a part of energy of a blue light photon (λ=450 nm) was transformed in some other form of energy. Finally, as a result of this process,:

Answer 29

the resulting photon can represent the violet light

Question 30

If the number of protons inside an atom nucleus lowers by one, it is possible that the nucleus emitted only this single particle (except of neutrinos and antineutrions)

Answer 30

β+

Question 31

Which of the following sets of quantities contains only vectors?

Answer 31

impulse of force, magnetic field (induction), momentum

Question 32

The term pV, where p is gas pressure, and V its volume, has the same unit as:

Answer 32

Energy

Question 33

A body hanging on a string oscillates harmonically without damping (moving up and down with a constant amplitude). The body reaches the maximum speed just when:

Answer 33

The body reaches minimum displacement (measured from the equilibrium position).

Question 34

The light rays travel through a converging lens and intersect in a singel point on principal axis of the lens 80cm in distance from the centre of the lens. This distance is twice of its focal length. The point source of these rays is located on the principal axis of the lens:

Answer 34

No answer is correct

Question 35

Intensity of a homogeneous electric field existing between the plates of a capacitor (at a constant voltage) is always:

Answer 35

not influenced by the relative permittivity of dielectric between the plates

Question 36

In the formula for the law of radioactive decay (Nt= N0 x e-λ x t) the right meaning of symbol λ is:

Answer 36

The decay constant

Question 37

Water is flowing through a horizontal pipe or varying radius. If the ratio of radii of the pipe in the narrower and broader part is 1:3, the ratio of water stream speed in these two parts must be:

Answer 37

9:1

Question 38

Which of the following units is the unit of dioptric power?

Answer 38

m-1

Question 39

A flat metallic block and a sphere made of the same metal are on the bottom of a vessel filled by water. Both bodies are of the same mass. It is true that:

Answer 39

Tre sphere will be bouyed uo more than the block