Thursday, 8 December 2011

Science Year 5 - Unit 5 Electricity

We depend on electricity in our daily lives. Electricity has made our lives easier and more comfortable. There are many sources of electricity. Many appliances in our homes and schools use electricity. However. we must be very careful when using electrical appliances. Why?

Some electrical appliances use dry cells to make them work. Dry cells produce electricity. There are also other sources of electricity such as accumulator, dynamo and solar cell. They are examples of batteries.

Accumulators are used in vehicles such as motorcycles, cars and lorries. Dynamos generate electricity. They are used to light up the bulb of bicycle. Satellites get their electricity from solar cells. Solar cells transform light energy into electricity. We can also get electricity from hydroelectric power sation.

An electrical circuit is made up of a power source, wires and other components such as a bulb and a switch. The dry cell is a source of electrical energy for the circuit. A switch is used to break or complete a circuit. The wire allows electricity to flow through the circuit. The bulb lights up because electricity flows through it.

Electricity is useful in our everyday life. Electrical appliances need proper handling because they can cause injury if they are not used properly. Mishandling of electrical appliances can cause. There are safety precautions that must be taken when using electrical appliances.
  • Do not touch switches with wet hands.
  • Do not connect too many electrical appliances to one power point.
  • Do not repair electrical appliances by yourself.
  • Do not use electrical appliances that are faulty.
Science Exercise 1 for Unit 5

Science Exercise 2 for Unit 5

Science Exercise 3 for Unit 5

Science Exercise 4 for Unit 5

Wednesday, 7 December 2011

Science Year 5 - Unit 4 Energy

Energy is important to our lives. We use energy to do work. Energy lights up our cities. Energy moves our cars, trains and enables us to watch televisions. What would happen if there is no energy?

Living things carry out life processess. Energy is needed to carry out these processes. Energy is also needed by non-living things. The energy is used to make them usable.

The Sun gives us heat and light energy. Plants use sunlight to make food. Humans and animals get energy form the food they eat. Their sources of food include plants and other animals.

Fuels such as coal, petroleum and natural gas are sources of energy too. These fuels are formed from dead plants and animals that lived millions of years ago.

Energy is found in different forms. The batteries in a toy car produce electrical energy to move it. Objects that move have kinetic energy. A burning candle gives off light energy and heat energy. A strectched rubber band in a catapult has potential energuy.

Energy can be transformed form one form to another. Switching on the light transforms electrical energy into light energy. A burning candle transforms chemical energy into light energy and heat energy. Solar powered signal light uses sunlight as the source of energy. The solar energy is transformed into electrical energy and then into light energy.

The energy we use everyday comes from various resources. These resources are divided into renewable energy and non-renewable energy.

Science Exercise 1 for Unit 4

Science Exercise 2 for Unit 4

Science Exercise 3 for Unit 4

Science Exercise 4 for Unit 4