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1
Q

random errors and systematic errors

A

different magnitudes and signs (RANDOM)

same magnitude and sign when measurements are repeated (SYSTEMATIC)

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2
Q

accuracy and precision

A

how close a measured value is to the true value

how close the repeated measured values are to each other, without regard to the true value

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3
Q

newton’s first law of motion

A

that when a body will continue in it state of rest or move with uniform velocity unless a resultant force acts on it

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4
Q

newton’s second law of motion

A

the resultant force acting on the body is proportional to the rate of change of it momentum, and the change takes place in the direction of the resultant force

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5
Q

newton’s third law of motion

A

is body A exerts a force on body B, then body B will exert a force of the same type, of equal magnitude but in the opposite direction on body A

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6
Q

linear momentum

A

product of its mass and its velocity

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7
Q

impulse

A

product of the force and time during which the force acts

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8
Q

principle of conservation of momentum

A

total momentum of a system remains constant provided no resultant external force acts on the system

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9
Q

moments

A

product of the force and the perpendicular distance of the line of action of the force from the pivot

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10
Q

couple

A

pair of forces which tends to produce rotation only

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11
Q

torque of a couple

A

product of one of the forces and the perpendicular distance between the lines of action of the forces

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12
Q

conditions for static equilibrium

A
  1. resultant force in any direction must be zero

2. resultant torque about any axis must be zero

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13
Q

principle of moments

A

for any object to be in rotational equilibrium, the sum of clockwise moments about any axis must be equal to the sum of anticlockwise moments about the same axis

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14
Q

work done

A

product of the force and the displacement of the body in the direction of the force

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15
Q

principle of conservation of energy

A

energy can only be transformed from one form to another, but i cannot be created or destroyed

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16
Q

power

A

work done per unit time

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17
Q

origin of upthrust

A
  1. pressure increases with depth in the fluid
  2. pressure on the bottom surface is larger than the pressure on the top surface, resulting in a pressure difference
  3. the difference in pressure causes an upward force called upthrust
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18
Q

one radian

A

it is the angle subtended at the centre of the circle by an arc equal in length to the radius of the circle

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19
Q

angular velocity

A

rate of change of angular displacement

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20
Q

simple harmonic motion

A

it is the periodic motion of a particle whose acceleration is proportional to its displacement from a fixed point, and is directed towards the point

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21
Q

resonance

A

it is the phenomenon in which a system responds at maximum amplitude to an external driving force of the same frequency as the natural frequency of the system. at resonance, there is maximum transfer of energy from the driving system into the oscillating system

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22
Q

amplitude

A

maximum displacement of the particle from its equilibrium position

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23
Q

wavelength

A

distance between two successive points in a wave which are in phase

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24
Q

period

A

time taken for one complete oscillation

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25
Q

frequency

A

number of oscillations per unit time

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26
Q

progressive wave

A

it transfers energy from the source in the direction of its propagation

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27
Q

transverse wave

A

where the direction of oscillations of particles is perpendicular to the direction of energy transfer of the wave

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28
Q

longitudinal wave

A

where the direction of oscillation of particles is parallel to the direction of energy transfer of the wave

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29
Q

intensity

A

rate of power per unit area perpendicular to the direction of wave propagation

30
Q

polarisation

A

when particles in the wave oscillate only in a single direction perpendicular to the direction of energy transfer of the wave

31
Q

principle of superposition

A

when two or more waves of the same kind overlap, the resultant displacement at any point at any instant is the vector sum of the displacements that individual waves would have separately produced at that point and at that instant

32
Q

interference

A

the phenomenon which occurs when two or more waves overlap according to the principle of superposition

33
Q

conditions for observable interference

A

overlapping waves must be coherent (same phase difference and same frequency)
for transverse waves, they must be either unpolarised or polarised in the same plane

34
Q

coherent

A

constant phase difference between them and have same frequency

35
Q

diffraction

A

spreading of waves after they pass through a small opening or round an obstacle

36
Q

rayleigh’s criterion

A

when the central maximum falls on the first minimum of another image and the images are distinguishable and said to be just resolved

37
Q

how a stationary wave is formed

A

it is the result of interference between two identical waves travelling along the same line with the same speeds but in opposite directions

38
Q

how are stationary waves formed (IGNORE)

A
  1. have a wave source that produce waves in the system
  2. waves are formed when reflection of the waves occurs at the ends of the system
  3. when a progressive wave encounters a boundary, reflection occurs. reflected wave is identical as the incident wave
39
Q

gravitational field

A

a region of space in which a mass experiences a gravitational force

40
Q

newton’s law of gravitation

A

states that two point masses attract each other with a force that is proportional to the product of the masses and inversely proportional to the square of their seperation

41
Q

geostationary orbit

A

allows the satellite to remain stationary relative to an observer on earth

42
Q

gravitational field strength

A

it is the gravitational force per unit mass acting on a small mass placed at that point

43
Q

gravitational potential

A

it is the work done per unit mass by an external force in bringing a small test mass from infinity to that point without a change in kinetic energy

44
Q

thermal equilibrium

A

when there is no heat flow between two objects in thermal contact and they have the same temperature

45
Q

specific heat capacity

A

heat energy required per unit mass per unit increase in the temperature of the substance without any change in phase

46
Q

specific latent heat of fusion

A

heat energy required per unit mass of a substance to change it from solid to liquid without any change in temperature

47
Q

specific latent heat of vaporisation

A

heat energy required per unit mass of a substance to change it from liquid to vapour without any change in temperature

48
Q

internal energy of a system

A

sum of random distribution of kinetic and potential energies of molecules in random motion

49
Q

first law of thermodynamics

A

increase in internal energy of a system is equal to the sum of heat supplied to the system and the work done on the system

50
Q

electric field

A

region in space where a charge experiences an electric force

51
Q

electric field strength

A

electric force per unit charge acting on a small stationary charge placed at that point

52
Q

electric potential

A

it is the work done per unit positive charge by an external force in bringing a small test charge from infinity to that point without a change in kinetic energy of the charge

53
Q

electric field strength

A

is numerically equal to the potential gradient at that point

54
Q

electric current

A

rate of flow of charge

55
Q

emf

A

energy converted from other forms to electrical energy per unit charge

56
Q

potential difference

A

electrical energy converted to other forms of energy per unit charge passing through that device

57
Q

resistance

A

ratio of potential difference across the component to the current flowing through it

58
Q

magnetic field

A

region in space where a permanent magnet or a moving charge or a current carrying conductor will experience a magnetic force

59
Q

magnetic flux density

A

magnetic flux density is the force per unit length per unit current acting on a straight current carrying conductor placed at right angles to the magnetic field

60
Q

magnetic flux

A

magnetic flux through a plane surface is the product of the magnetic density normal to the surface and the area of the surface

61
Q

magnetic flux linkage

A

product of the number of turns and the magnetic flux linking each turn

62
Q

faraday’s law of electromagnetic induction

A

induced emf is directly proportional to the rate of change of magnetic flux linkage

63
Q

lenz’ law

A

the direction of the induced emf is such as to cause effects to oppose the change producing it

64
Q

rms current

A

it is the value of an equivalent steady direct current that would provide the same average power as the alternating current

65
Q

photon

A

discrete bundle of electromagnetic energy

66
Q

photoelectric effect

A

phenomenon where electrons are emitted from a metal surface when electromagnetic radiation of sufficiently high frequency is incident on the metal surface

67
Q

work function energy

A

minimum amount of energy necessary to remove an electron from the surface of the material

68
Q

threshold frequency

A

minimum frequency of the electromagnetic radiation incident on a metal surface for the electron to escape

69
Q

stopping potential

A

minimum retarding potential to stop all electrons from reaching the collector plate

70
Q

emission line spectrum and how they are produced

A

consists of discrete bright coloured lines in a dark background

gases can be placed in a discharge tube at low pressure. voltage in kV applied between electrodes in the tube which is large enough to produce an electric current in the gas.
the gas becomes excited by the collisions with the electrons passing through the tube, from cathode to anode of the discharge tube.
excited gas atoms are unstable. when the gas atoms transits to a lower energy level, the excess energy is emitted as a photon with a specific frequency.
the frequency of the emission line is dependent on the energy difference between the high and low energy levels, only certain high to low energy level transitions are possible within the atom, therefore only certain frequency lines are present in the spectrum.

71
Q

absorption line spectrum and

A

dark lines against a continuous spectrum of the white light

it is produced when white light containing all frequencies passes through a cold gas
those incident photons whose energies are exactly equal to the difference between the atom’s energy levels are being absorbed. since energy levels are discrete, only photons of certain frequencies are absorbed
when the atoms transit back to ground state, the photons of the same frequencies are then reradiated but in ALL DIRECTIONS hence part corresponding to these wavelengths appear dark

physics definitions (1 decks)

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