Question

(a) An electric heater is used to heat a classroom in a school.
The arrows on Fig. 12.1 show the circulation of air around the classroom.
P and Q are two positions within the air circulation.

Complete the sentences using words from the list.
conduction           convection           cooled                       radiation                 warmed
Position P shows ………………………………. air.
Position Q shows ………………………………. air.
This method of thermal energy transfer is called ………………………………. .

(b) In the classroom, a student draws diagrams to represent the three states of matter.
Fig. 12.2 shows the diagrams drawn. Box X shows the arrangement of particles in a solid.
Box Y shows the arrangement of particles in a liquid.

(i) In box Z, draw the arrangement of particles in a gas. 
(ii) Complete the sentences below using only the words solid, liquid and gas.
Solidification occurs when a …………………………….. turns into a …………………………….. .
Condensation occurs when a …………………………….. turns into a …………………………….. .
(iii) State the melting point and the boiling point of water at standard atmospheric pressure.
melting point = ……………….. °C
boiling point = ………………… °C

(c) In another lesson, the student builds an electric circuit.
Fig. 12.3 shows the circuit diagram.

(i) State the name of the components represented by the symbols in Table 12.1.

(ii) When there is a potential difference of 6V across the lamp, a current of 0.3A passes through the lamp.

Calculate the resistance of the lamp.

                                                                                         resistance = …………………………………………….. Ω