​ A ray of light incident on the surface of a glass prism is observed to behave as represented in the diagram in figure 6

​Explain this observation ( 3 mks)

​Light travels through glass of  refractive index 1.5 with a speed v.
​Calculate the value of v.

K.N.E.C Marking Scheme

​The diagram in figure 5 shows a beam negligible weight balanced by constant forces P and Q.

State two ways by which the frequency of a note produced by a given guitar wire may be increased.

​Give a reason why attraction in magnesium is not regarded as a reliable method of testing for polarity.

The force on a conductor carrying a current in a magnetic  field can be varied by changing, among others, the magnitude of the current and the magnetic field strength. Name two other factors that can be changed to vary the force. (2 mks)

The diagram in figure 4 shows two glass tubes of different diameters dipped in water

State two advantages  of an alkaline battery over a lead acid battery (2 mks)

You are provided with a charged electroscope, an insulator and a conductor. Describe how you would use these apparatus to distinguish  in the insulator from the conductor (2 mks)

In the set up shown in figure 3, water near the top of the boiling tube boils while at the bottom it remains cold.

Give a reason for the observation (1mk)

What property of light is suggested by the formation of shadows?   (1 mks)

One property of a liquid that is considered while construction a liquid – in – glass thermometer is that the liquid expands more than the glass for the same temperature change. State any other two properties of the liquids that are considered (2 mks)

​State the assumption made when calculating the size of a molecule in the thin oil film experiment.

​Figure 2 shows a liquid being siphoned from one beaker to another. Refer to this diagram where answering questions 4, 5 and 6

Figure 1 shows a worker ready to lift a load wheelbarrow.

Use the figure to answer questions 2 and 3

KNEC ANSWERS

2)

3) Effort would reduce

​Name the instrument that would be most suitable for measuring the thickest of one sheet of this question paper.