Tests

• Frequency


  The number of cycles of a periodic wave occurring per unit time
• Electromagnetic waves of wavelength λ and frequency f travel at speed c in a vacuum


  Electromagnetic waves of frequency f/2 have wavelength 2λ and travel at speed c
• Longitudinal wave


  Particles of the medium vibrate to and from in the same direction of energy transport
• Transverse wave


  Particles of the medium vibrate at right angles to the direction of energy transport
• The graph represents a stationary wave at two different times (X & Y)
• A light wave travelling through air is a longitudinal wave
• A radio wave from a broadcasting station is a longitudinal wave
• A ripple on the surface of water is a transverse wave
• A sound wave travelling through air is a longitudinal wave
• Diffraction


  The bending of waves round an obstacle
• Wave X has amplitude 8 cm and frequency 100 Hz
• Wave Y has the same amplitude and frequency as wave X
• As a pulse travels through a uniform medium, the speed of the pulse remains the same
• Speed of a sound wave

  Depends on the properties of the medium
• When light passes from air into glass, the frequency remains the same but the wavelength and speed change
• In a standing wave, the vibrations of the medium occur at the antinodes
• The distance between the first and sixth node of a stationary sound wave is 30.0 cm, so the wavelength is 6.0 cm
• Electrons do not travel at the speed of light in a vacuum
• If two objects are in thermal equilibrium, they must be at the same temperature
• The zeroth law of thermodynamics states that if object C is in thermal equilibrium with both object A and object B, then A and B must also be in thermal equilibrium
• The zeroth law allows us to define temperature
• Room temperature is about 20 degrees Celsius
• The fact that gases exert pressure on the walls of their containers is evidence that a gas consists mostly of empty space
• An isothermal process for an ideal gas is represented on a p-V diagram by a hyperbola
• A balloon filled with cold air placed in a warm room is not in thermal equilibrium with the air of the room until it stops expanding
• The two metallic strips that constitute some thermostats must differ in their coefficient of linear expansion
• A gram of distilled water at 4°C will increase slightly in volume when heated to 6°C
• Pressure of a gas

  Due to the change of momentum of molecules as they strike the wall
• Increasing the pressure of a gas decreases its volume
• Gases are highly compressible due to the large distance between their particles
• Kinetic energy is directly proportional to temperature
• The internal energy of an ideal gas depends on temperature, pressure, and volume
• Solids have the strongest intermolecular forces of attraction
• To make an uncharged object have a positive charge, you must remove some electrons
• An electromagnetic field exists when there is a current
• The units of 1/4πε0 are N·m2/C2
• An electrical insulator is a material through which electrons do not flow easily
• Electrical conductors contain both free and bound electrons
• A coulomb is the same as an ampere·second
• Current


  The number of coulombs of charges that passes any section of the conductors in one second