The voltage - current readings of a certain material are shown in the table given below :

Study the table.

(a) State whether the conductor used is ohmic or non-ohmic.

(b) Justify your answer.

(c) State Ohm’s law.

Below is the diagram of a transformer :

(a) Identify the type of transformer.

(b) In this type of transformer which of the wire is thicker, the primary or the secondary? Give a reason.

85 g of water at 30°C is cooled to 5°C by adding certain mass of ice. Find the mass of ice required.

[Specific heat capacity of water = 4.2 J g⁻¹ °C⁻¹ , Specific latent heat of fusion = 336 J g⁻¹]

(a) Why does it become pleasantly warm when the lakes start freezing?

(b) Water freezes to form ice. What change would you expect in the average kinetic energy of the molecules?

(c) Which will contain more heat energy 1 g of ice at 0°C or 1 g water at 0°C ?