Question

Amy buys a laptop charger in Barbados. On the back it says rated for for Barbados 115Volts. Explain whether there has been a mistake. Show calculation to support answer. Refer to EMS

Answer 1

Here, we are given a velocity-time graph which shows how the main voltage varies in Barbados.

Let's solve for the following:

• (a) What is the peak voltage.

Peak voltage can be said to be the highest point of voltage.

From the given graph, the peak voltage is 160 volts.

• (b) What is the frequency.

To find the frequency, apply the formula:

`F=(1)/(T)`

Where:

T is the time taken to complete one full revolution.

Here, T = 0.02 seconds

Hence, we have:

`\begin{gathered} F=(1)/(0.02) \\ \\ F=50\text{ Hz} \end{gathered}`

The frequency is 50 Hz.

• (c) Amy buys a laptop charger in Barbados. On the back it says rated for for Barbados 115Volts. Explain whether there has been a mistake.

In appliances, the RMS voltage is always written on the back.

To find the RMS volatge using the graph, we have:

`V_(RMS)=\frac{V_o}{\sqrt[]{2}}`

Where Vo is the peak voltage = 160 v.

Hence, we have:

`\begin{gathered} V_{\text{RMS}}=\frac{160}{\sqrt[]{2}} \\ \\ V_{\text{RMS}}=113.14\text{ v} \end{gathered}`

In this case, the rated voltage on the back of the charger is 115 volts where the RMS voltage is 113.14 volts. Therefore, we can say there is a mistake.