phys

• How can unwanted energy transfers be reduced in a system?

  Lubrication and thermal insulation
• Match the method of energy transfer with its effect:

  Conduction ↔️ Energy transfer through material

  Thermal insulation ↔️ Reduces energy loss

  Lubrication ↔️ Reduces friction
• Name three main energy resources available on Earth.

  Fossil fuels, wind, solar
• A renewable energy resource is one that is being replenished as it is being used
• Why are some energy resources more reliable than others?

  Availability and consistency
• What happens to the resistance of a filament lamp as its temperature increases?

  It increases
• What happens to the resistance of a thermistor as temperature increases?

  It decreases
• What happens to the resistance of an LDR as light intensity increases?

  It decreases
• Steps to investigate the I–V characteristics of circuit elements

  1️⃣ Use circuit diagrams to construct circuits

  2️⃣ Investigate a filament lamp

  3️⃣ Investigate a diode

  4️⃣ Investigate a resistor at constant temperature
• The unit of resistance is the ohm
• In a parallel circuit, the potential difference across each component is the same.
• What happens to the total resistance when resistors are added in parallel?

  It decreases
• What is the color of the live wire in a three-core cable?

  Brown
• The earth wire in a three-core cable is colored green and yellow.
• What is the potential difference between the live wire and earth?

  230 V
• The earth wire carries a current only if there is a fault.
• Power is measured in watts.
• Steps in the energy transfer process in everyday appliances

  1️⃣ Appliance is switched on

  2️⃣ Electrical energy is converted to other forms

  3️⃣ Energy is transferred over time
• What is the role of step-up transformers in the National Grid?

  Increase potential difference
• Step-down transformers are used in the National Grid to decrease the potential difference for domestic use.
• The National Grid is an efficient way to transfer energy because it reduces energy loss.
• The density of a material is measured in kilograms per metre cubed
• What happens when certain insulating materials are rubbed together in static electricity?

  Electrons are transferred
• The material that gains electrons becomes negatively charged.
• Objects with the same type of charge repel each other.
• Steps in the process of static electricity production

  1️⃣ Insulating materials are rubbed together

  2️⃣ Electrons are transferred

  3️⃣ One material becomes positively charged, the other negatively charged
• The particle model can explain the differences in density between solids, liquids, and gases.
• Steps to determine the density of an irregular solid object using the displacement technique

  1️⃣ Measure the mass of the object

  2️⃣ Measure the initial volume of water in a container

  3️⃣ Place the object into the water

  4️⃣ Measure the final volume of water

  5️⃣ Calculate the volume of the object
• What creates an electric field around a charged object?

  The charged object itself
• The electric field is strongest closest to the charged object.
• A charged object placed in an electric field experiences a force.
• What happens to mass when a substance changes state?

  It is conserved
• Changes of state are examples of physical changes.
• In a change of state, the material recovers its original properties if reversed.
• What is internal energy defined as?

  Total kinetic and potential energy
• Heating a system increases the internal energy of the particles.
• Heating can either raise the temperature or produce a change of state.
• The specific heat capacity is the energy required to raise the temperature of one kilogram of a substance by one degree Celsius.
• What is latent heat required for during a change of state?

  To change state without temperature change
• The specific latent heat of fusion applies to the change from solid to liquid.