Flashcards
P1 - Part 1
Cards in this deck (20)
- 1What is the difference between heat and temperature?The hotter an object is, the faster the motion of the molecules inside it. Thus, the heat of an object is the total energy of all the molecular motion inside that object. Temperature, on the other hand, is a measure of the average heat or thermal energy of the molecules in a substance.
- 2How does energy flow?Energy, in the form of heat, flows from a warmer to colder body like if you place an ice cube on your hand, it melts as well as your hand getting colder. This is because the heat in your hand has flown to the ice melting it.
- 3What is Specific Heat Capacity?The specific heat capacity of a substance is the amount of energy needed to change the temperature of 1 kg of the substance by 1°C. Different substances have different specific heat capacities.
- 4What is Specific Latent Heat?The specific latent heat of fusion, of a substance is the heat needed to change a mass of 1 kg the substance from a solid at its melting point into liquid at the same temperature. The specific latent heat of evaporation is is the heat needed to change a mass of 1 kg the substance from a solid to a gas
- 5How does double glazing insulate the house?The air gap is too small to allow the air to circulate. This prevents heat transfer by convection. The trapped air is a very poor conductor which reduces the rate of heat loss through the window. The room in the house stays warmer for longer
- 6How does cavity wall insulation and loft insulation insulate the house?Heat loss through walls can be reduced using cavity wall insulation. This involves blowing insulating material into the gap between the brick and the inside wall, which reduces the heat loss by conduction. The material also prevents air circulating inside the cavity, therefore reducing heat loss by convection.Heat loss through the roof can be reduced by laying loft insulation. This works in a similar way to cavity wall insulation.
- 7What is conduction?Heat energy is passed on in a substance by particles bumping into neighboring particles and passing on the extra energy.
- 8How does conduction work in metals?The electrons in piece of metal can leave their atoms and move about in the metal as free electrons. The parts of the metal atoms left behind are now charged metal ions. The ions are packed closely together and they vibrate continually. The hotter the metal, the more kinetic energy these vibrations have. This kinetic energy is transferred from hot parts of the metal to cooler parts by the free electrons. These move through the structure of the metal, colliding with ions as they go.
- 9What is radiation?Heat can be transferred by infrared radiation. Unlike conduction and convection, which need particles, infrared radiation is a type of electromagnetic radiation that involves waves. Radiation can even work through the vacuum of space. This is why we can still feel the heat of the Sun even though it is 150 million km away from the Earth.
- 10What is convection?Liquids and gases are fluids. The particles in these fluids can move from place to place. Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection
- 11What is the efficiency equation?Useful energy output
Total energy input
(x100%) - 12What is the payback time equation?cost of insulation
annual saving - 13What small things save energy at home?Closing the curtains cuts down energy loss through windows
putting aluminium foil behind the radiators helps reflect the heat back inside the house
Draught strips around windows and doors are cheap and effective - 14Describe all the parts of a transverse wave
- 15What is the amplitude?It is the maximum displacement of a particle from its rest position
- 16What is the wavelength?It is the distance between two successive points on the wave having the same displacement and moving in the same direction. The unit is metre (m)
- 17What is the frequency?It is the number of complete waves passing a point in 1 second. The unit is hertz (Hz)
- 18What is the trough and crest of a wave?The crest is the actual point of maximum displacement above the rest position.
The trough is the maximum displacement below the rest position. - 19How do you calculate the speed of a wave?Frequency x Wavelength
- 20Name, in order from lowest to highest frequency, the electromagnetic spectrum
