K A Tsokos Solutions for Chapter: Waves, Exercise 3: Test yourself

The diagram shows two pulses of equal width and height travelling in opposite directions on the same string. Draw the shape of the string when the pulses completely overlap.

The wave pulses shown in the diagram travel at $1 \mathrm{cm} {\mathrm{s}}^{-1}$ and both have width $2 \mathrm{cm}$. The heights are indicated on the diagram. In each case, draw the shape of the resulting pulse according to the principle of superposition at times $t=0.5 \mathrm{s}$, $t=1.0 \mathrm{s}$ and $t=1.5 \mathrm{s}$. Take $t=0 \mathrm{s}$ to be the time when the pulses are about to meet each other.

Two waves are simultaneously generated on a string. The graph shows the variation of displacement $y$ with distance $x$. Draw the actual shape of the string.

State what is meant by polarised light.

State two methods by which light can be polarised.

Suggest why only transverse waves can be polarised.

State Malus’s law.

Polarised light is incident on a polariser whose transmission axis makes an angle of $25°$ with the direction of the electric field of the incident light. Calculate the fraction of the incident light intensity that is transmitted through the polariser.